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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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2
Task/Read-a-specific-line-from-a-file/00-META.yaml Normal file
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---
from: http://rosettacode.org/wiki/Read_a_specific_line_from_a_file

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Task/Read-a-specific-line-from-a-file/00-TASK.txt Normal file
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Some languages have special semantics for obtaining a known line number from a file.
;Task:
Demonstrate how to obtain the contents of a specific line within a file.
For the purpose of this task demonstrate how the contents of the seventh line of a file can be obtained,   and store it in a variable or in memory   (for potential future use within the program if the code were to become embedded).
If the file does not contain seven lines,   or the seventh line is empty,   or too big to be retrieved,   output an appropriate message.
If no special semantics are available for obtaining the required line,   it is permissible to read line by line.
Note that empty lines are considered and should still be counted.
Also note that for functional languages or languages without variables or storage,   it is permissible to output the extracted data to standard output.
<br><br>

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Task/Read-a-specific-line-from-a-file/11l/read-a-specific-line-from-a-file.11l Normal file
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V f = File(‘input.txt’)
V line = 3
L 0 .< line - 1
f.read_line()
print(f.read_line())

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Task/Read-a-specific-line-from-a-file/ALGOL-68/read-a-specific-line-from-a-file.alg Normal file
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# reads the line with number "number" (counting from 1) #
# from the file named "file name" and returns the text of the #
# in "line". If an error occurs, the result is FALSE and a #
# message is returned in "err". If no error occurs, TRUE is #
# returned #
PROC read specific line = ( STRING file name
, INT number # line 7 #
, REF STRING line
, REF STRING err
)BOOL:
IF FILE input file;
line := "";
open( input file, file name, stand in channel ) /= 0
THEN
# failed to open the file #
err := "Unable to open """ + file name + """";
FALSE
ELSE
# file opened OK #
err := "";
BOOL at eof := FALSE;
# set the EOF handler for the file #
on logical file end( input file
, ( REF FILE f )BOOL:
BEGIN
# note that we reached EOF on the #
# latest read #
at eof := TRUE;
# return TRUE so processing can continue #
TRUE
END
);
INT line number := 0;
STRING text;
WHILE line number < number
AND NOT at eof
DO
get( input file, ( text, newline ) );
line number +:= 1
OD;
# close the file #
close( input file );
# return the line or an error message depending on whether #
# we got a line with the required number or not #
IF line number = number
THEN
# got the required line #
line := text;
TRUE
ELSE
# not enough lines in the file #
err := """" + file name + """ is too short";
FALSE
FI
FI; # read specific line #
main:(
# read the seventh line of this source and print it #
# (or an error message if we can't) #
STRING line;
STRING err;
IF read specific line( "read-specific-line.a68", 7, line, err )
THEN
# got the line #
print( ( "line seven is: """ + line + """", newline ) )
ELSE
# got an error #
print( ( "unable to read line: """ + err + """" ) )
FI
)

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Task/Read-a-specific-line-from-a-file/AWK/read-a-specific-line-from-a-file.awk Normal file
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#!/usr/bin/awk -f
#usage: readnthline.awk -v lineno=6 filename
FNR==lineno { storedline=$0; found++ }
END {
if (found < 1) {
print "ERROR: Line", lineno, "not found"
exit 1
}
print storedline
}

46
Task/Read-a-specific-line-from-a-file/Action-/read-a-specific-line-from-a-file.action Normal file
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BYTE FUNC ReadLine(CHAR ARRAY fname CARD index CHAR ARRAY result)
CHAR ARRAY line(255)
CARD curr
BYTE status,dev=[1]
Close(dev)
Open(dev,fname,4)
curr=1 status=1
WHILE Eof(dev)=0
DO
InputSD(dev,line)
IF curr=index THEN
SCopy(result,line)
status=0
EXIT
FI
curr==+1
OD
Close(dev)
RETURN (status)
PROC Test(CHAR ARRAY fname CARD index)
CHAR ARRAY result(255)
BYTE status
PrintF("Reading %U line...%E",index)
status=ReadLine(fname,index,result)
IF status=0 THEN
IF result(0)=0 THEN
PrintF("%U line is empty.%E%E",index)
ELSE
PrintF("%U line is:%E""%S""%E%E",index,result)
FI
ELSEIF status=1 THEN
PrintF("File contains less than %U lines.%E%E",index)
FI
RETURN
PROC Main()
CHAR ARRAY fname="H6:READ__96.ACT"
PrintF("Reading ""%S""...%E%E",fname)
Test(fname,7)
Test(fname,24)
Test(fname,50)
RETURN

29
Task/Read-a-specific-line-from-a-file/Ada/read-a-specific-line-from-a-file.ada Normal file
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with Ada.Text_IO; use Ada.Text_IO;
procedure Rosetta_Read is
File : File_Type;
begin
Open (File => File,
Mode => In_File,
Name => "rosetta_read.adb");
Set_Line (File, To => 7);
declare
Line_7 : constant String := Get_Line (File);
begin
if Line_7'Length = 0 then
Put_Line ("Line 7 is empty.");
else
Put_Line (Line_7);
end if;
end;
Close (File);
exception
when End_Error =>
Put_Line ("The file contains fewer than 7 lines.");
Close (File);
when Storage_Error =>
Put_Line ("Line 7 is too long to load.");
Close (File);
end Rosetta_Read;

26
Task/Read-a-specific-line-from-a-file/Aime/read-a-specific-line-from-a-file.aime Normal file
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void
read_line(text &line, text path, integer n)
{
file f;
f.affix(path);
call_n(n, f_slip, f);
f.line(line);
}
integer
main(void)
{
if (1 < argc()) {
text line;
read_line(line, argv(1), 6);
o_("7th line is:\n", line, "\n");
}
0;
}

15
Task/Read-a-specific-line-from-a-file/Amazing-Hopper/read-a-specific-line-from-a-file.hopper Normal file
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#include <hopper.h>
#define MAX_LINE_SIZE 1000
main:
v=0, fd=0
fsearch("-r $'\n'","archivo.txt")(v)
fopen(OPEN_READ,"archivo.txt")(fd)
{"Line #7 = "}, fgetsline(fd,MAX_LINE_SIZE,7,v), println
try
fgetsline(fd,MAX_LINE_SIZE,10,v),
catch(e)
{"Error search line (code=",e,"): "},get str error
finish
println
fclose(fd)
exit(0)

5
Task/Read-a-specific-line-from-a-file/Arturo/read-a-specific-line-from-a-file.arturo Normal file
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lineToRead: 3
lineRead: get read.lines "myfile.txt" lineToRead
print lineRead

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Task/Read-a-specific-line-from-a-file/AutoHotkey/read-a-specific-line-from-a-file.ahk Normal file
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FileReadLine, OutputVar, filename.txt, 7
if ErrorLevel
MsgBox, There was an error reading the 7th line of the file

17
Task/Read-a-specific-line-from-a-file/BASIC256/read-a-specific-line-from-a-file.basic Normal file
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f = freefile
filename$ = "input.txt"
open f, filename$
lineapedida = 7
cont = 0
while not (eof(f))
linea$ = readline(f)
cont += 1
if cont = lineapedida then
if trim(linea$) = "" then print "The 7th line is empty" else print linea$
exit while
end if
end while
if cont < lineapedida then print "There are only "; cont; " lines in the file"
close f
end

13
Task/Read-a-specific-line-from-a-file/BBC-BASIC/read-a-specific-line-from-a-file.basic Normal file
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filepath$ = @lib$ + "..\licence.txt"
requiredline% = 7
file% = OPENIN(filepath$)
IF file%=0 ERROR 100, "File could not be opened"
FOR i% = 1 TO requiredline%
IF EOF#file% ERROR 100, "File contains too few lines"
INPUT #file%, text$
NEXT
CLOSE #file%
IF ASCtext$=10 text$ = MID$(text$,2)
PRINT text$

9
Task/Read-a-specific-line-from-a-file/Batch-File/read-a-specific-line-from-a-file.bat Normal file
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@echo off
for /f "skip=6 tokens=*" %%i in (file.txt) do (
set line7=%%i
goto break
)
:break
echo Line 7 is: %line7%
pause>nul

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Task/Read-a-specific-line-from-a-file/C++/read-a-specific-line-from-a-file.cpp Normal file
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#include <string>
#include <fstream>
#include <iostream>
int main( ) {
std::cout << "Which file do you want to look at ?\n" ;
std::string input ;
std::getline( std::cin , input ) ;
std::ifstream infile( input.c_str( ) , std::ios::in ) ;
std::string file( input ) ;
std::cout << "Which file line do you want to see ? ( Give a number > 0 ) ?\n" ;
std::getline( std::cin , input ) ;
int linenumber = std::stoi( input ) ;
int lines_read = 0 ;
std::string line ;
if ( infile.is_open( ) ) {
while ( infile ) {
getline( infile , line ) ;
lines_read++ ;
if ( lines_read == linenumber ) {
std::cout << line << std::endl ;
break ;
}
}
infile.close( ) ;
if ( lines_read < linenumber )
std::cout << "No " << linenumber << " lines in " << file << " !\n" ;
return 0 ;
}
else {
std::cerr << "Could not find file " << file << " !\n" ;
return 1 ;
}
}

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Task/Read-a-specific-line-from-a-file/C-sharp/read-a-specific-line-from-a-file.cs Normal file
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using System;
using System.IO;
namespace GetLine
{
internal class Program
{
private static void Main(string[] args)
{
Console.WriteLine(GetLine(args[0], uint.Parse(args[1])));
}
private static string GetLine(string path, uint line)
{
using (var reader = new StreamReader(path))
{
try
{
for (uint i = 0; i <= line; i++)
{
if (reader.EndOfStream)
return string.Format("There {1} less than {0} line{2} in the file.", line,
((line == 1) ? "is" : "are"), ((line == 1) ? "" : "s"));
if (i == line)
return reader.ReadLine();
reader.ReadLine();
}
}
catch (IOException ex)
{
return ex.Message;
}
catch (OutOfMemoryException ex)
{
return ex.Message;
}
}
throw new Exception("Something bad happened.");
}
}
}

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Task/Read-a-specific-line-from-a-file/C/read-a-specific-line-from-a-file-1.c Normal file
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#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <err.h>
/* following code assumes all file operations succeed. In practice,
* return codes from open, close, fstat, mmap, munmap all need to be
* checked for error.
*/
int read_file_line(const char *path, int line_no)
{
struct stat s;
char *buf;
off_t start = -1, end = -1;
size_t i;
int ln, fd, ret = 1;
if (line_no == 1) start = 0;
else if (line_no < 1){
warn("line_no too small");
return 0; /* line_no starts at 1; less is error */
}
line_no--; /* back to zero based, easier */
fd = open(path, O_RDONLY);
fstat(fd, &s);
/* Map the whole file. If the file is huge (up to GBs), OS will swap
* pages in and out, and because search for lines goes sequentially
* and never accesses more than one page at a time, penalty is low.
* If the file is HUGE, such that OS can't find an address space to map
* it, we got a real problem. In practice one would repeatedly map small
* chunks, say 1MB at a time, and find the offsets of the line along the
* way. Although, if file is really so huge, the line itself can't be
* guaranteed small enough to be "stored in memory", so there.
*/
buf = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
/* optional; if the file is large, tell OS to read ahead */
madvise(buf, s.st_size, MADV_SEQUENTIAL);
for (i = ln = 0; i < s.st_size && ln <= line_no; i++) {
if (buf[i] != '\n') continue;
if (++ln == line_no) start = i + 1;
else if (ln == line_no + 1) end = i + 1;
}
if (start >= s.st_size || start < 0) {
warn("file does not have line %d", line_no + 1);
ret = 0;
} else {
/* do something with the line here, like
write(STDOUT_FILENO, buf + start, end - start);
or copy it out, or something
*/
}
munmap(buf, s.st_size);
close(fd);
return ret;
}

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Task/Read-a-specific-line-from-a-file/C/read-a-specific-line-from-a-file-2.c Normal file
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#include <stdio.h>
#include <stdlib.h>
#define BUF_SIZE ( 256 )
char *get_nth_line( FILE *f, int line_no )
{
char buf[ BUF_SIZE ];
size_t curr_alloc = BUF_SIZE, curr_ofs = 0;
char *line = malloc( BUF_SIZE );
int in_line = line_no == 1;
size_t bytes_read;
/* Illegal to ask for a line before the first one. */
if ( line_no < 1 )
return NULL;
/* Handle out-of-memory by returning NULL */
if ( !line )
return NULL;
/* Scan the file looking for newlines */
while ( line_no &&
( bytes_read = fread( buf, 1, BUF_SIZE, f ) ) > 0 )
{
int i;
for ( i = 0 ; i < bytes_read ; i++ )
{
if ( in_line )
{
if ( curr_ofs >= curr_alloc )
{
curr_alloc <<= 1;
line = realloc( line, curr_alloc );
if ( !line ) /* out of memory? */
return NULL;
}
line[ curr_ofs++ ] = buf[i];
}
if ( buf[i] == '\n' )
{
line_no--;
if ( line_no == 1 )
in_line = 1;
if ( line_no == 0 )
break;
}
}
}
/* Didn't find the line? */
if ( line_no != 0 )
{
free( line );
return NULL;
}
/* Resize allocated buffer to what's exactly needed by the string
and the terminating NUL character. Note that this code *keeps*
the terminating newline as part of the string.
*/
line = realloc( line, curr_ofs + 1 );
if ( !line ) /* out of memory? */
return NULL;
/* Add the terminating NUL. */
line[ curr_ofs ] = '\0';
/* Return the line. Caller is responsible for freeing it. */
return line;
}
/* Test program. Prints out the 7th line of input from stdin, if any */
int main( int argc, char *argv[] )
{
char *line7 = get_nth_line( stdin, 7 );
if ( line7 )
{
printf("The 7th line of input was:\n%s\n", line7 );
free( line7 );
} else
{
printf("Did not find the 7th line of input. Reason: ");
if ( feof( stdin ) )
puts("End of file reached.");
else if ( ferror( stdin ) )
puts("Error reading input.");
else
puts("Out of memory.");
}
return 0;
}

5
Task/Read-a-specific-line-from-a-file/Clojure/read-a-specific-line-from-a-file.clj Normal file
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(defn read-nth-line
"Read line-number from the given text file. The first line has the number 1."
[file line-number]
(with-open [rdr (clojure.java.io/reader file)]
(nth (line-seq rdr) (dec line-number))))

11
Task/Read-a-specific-line-from-a-file/Common-Lisp/read-a-specific-line-from-a-file.lisp Normal file
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(defun read-nth-line (file n &aux (line-number 0))
"Read the nth line from a text file. The first line has the number 1"
(assert (> n 0) (n))
(with-open-file (stream file)
(loop for line = (read-line stream nil nil)
if (and (null line) (< line-number n))
do (error "file ~a is too short, just ~a, not ~a lines long"
file line-number n)
do (incf line-number)
if (and line (= line-number n))
do (return line))))

6
Task/Read-a-specific-line-from-a-file/D/read-a-specific-line-from-a-file-1.d Normal file
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void main() {
import std.stdio, std.file, std.string;
auto file_lines = readText("input.txt").splitLines();
//file_lines becomes an array of strings, each line is one element
writeln((file_lines.length > 6) ? file_lines[6] : "line not found");
}

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Task/Read-a-specific-line-from-a-file/D/read-a-specific-line-from-a-file-2.d Normal file
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import std.stdio;
void main() {
int countLines;
char[] ln;
auto f = File("linenumber.d", "r");
foreach (char[] line; f.byLine()) {
countLines++;
if (countLines == 7) {
ln = line;
break;
}
}
switch(countLines) {
case 0 : writeln("the file has zero length");
break;
case 7 : writeln("line 7: ", (ln.length ? ln : "empty"));
break;
default :
writefln("the file only contains %d lines", countLines);
}
}

38
Task/Read-a-specific-line-from-a-file/Delphi/read-a-specific-line-from-a-file.delphi Normal file
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program Read_a_specific_line_from_a_file;
{$APPTYPE CONSOLE}
uses
System.SysUtils;
function ReadLine(position: Cardinal; FileName: TFileName): string;
begin
Result := '';
if not FileExists(FileName) then
raise Exception.Create('Error: File does not exist.');
var F: TextFile;
var line: string;
AssignFile(F, FileName);
Reset(F);
for var _ := 1 to position do
begin
if Eof(F) then
begin
CloseFile(F);
raise Exception.Create(Format('Error: The file "%s" is too short. Cannot read line %d',
[FileName, position]));
end;
Readln(F, line);
end;
CloseFile(F);
Result := line;
end;
begin
Writeln(ReadLine(7, 'test'));
Readln;
end.

11
Task/Read-a-specific-line-from-a-file/Elixir/read-a-specific-line-from-a-file.elixir Normal file
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defmodule LineReader do
def get_line(filename, line) do
File.stream!(filename)
|> Stream.with_index
|> Stream.filter(fn {_value, index} -> index == line-1 end)
|> Enum.at(0)
|> print_line
end
defp print_line({value, _line_number}), do: String.trim(value)
defp print_line(_), do: {:error, "Invalid Line"}
end

30
Task/Read-a-specific-line-from-a-file/Erlang/read-a-specific-line-from-a-file.erl Normal file
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-module( read_a_specific_line ).
-export( [from_file/2, task/0] ).
from_file( File, N ) -> line_nr( N, read_a_file_line_by_line:into_list(File) ).
task() ->
Lines = read_a_file_line_by_line:into_list( "read_a_specific_line.erl" ),
Line_7 = line_nr( 7, Lines ),
Line_7.
line_nr( N, Lines ) ->
try
case lists:nth( N, Lines )
of "\n" -> erlang:exit( empty_line )
; Line -> Line
end
catch
_Type:Error0 ->
Error = line_nr_error( Error0 ),
io:fwrite( "Error: ~p~n", [Error] ),
erlang:exit( Error )
end.
line_nr_error( function_clause ) -> too_few_lines_in_file;
line_nr_error( Error ) -> Error.

15
Task/Read-a-specific-line-from-a-file/F-Sharp/read-a-specific-line-from-a-file.fs Normal file
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open System
open System.IO
[<EntryPoint>]
let main args =
let n = Int32.Parse(args.[1]) - 1
use r = new StreamReader(args.[0])
let lines = Seq.unfold (
fun (reader : StreamReader) ->
if (reader.EndOfStream) then None
else Some(reader.ReadLine(), reader)) r
let line = Seq.nth n lines // Seq.nth throws an ArgumentException,
// if not not enough lines available
Console.WriteLine(line)
0

15
Task/Read-a-specific-line-from-a-file/Factor/read-a-specific-line-from-a-file.factor Normal file
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USING: continuations fry io io.encodings.utf8 io.files kernel
math ;
IN: rosetta-code.nth-line
: nth-line ( path encoding n -- str/f )
[ f ] 3dip '[
[ _ [ drop readln [ return ] unless* ] times ]
with-return
] with-file-reader ;
: nth-line-demo ( -- )
"input.txt" utf8 7 nth-line [ "line not found" ] unless*
print ;
MAIN: nth-line-demo

67
Task/Read-a-specific-line-from-a-file/Fortran/read-a-specific-line-from-a-file-1.f Normal file
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MODULE SAMPLER !To sample a record from a file. SAM00100
CONTAINS SAM00200
CHARACTER*20 FUNCTION GETREC(N,F,IS) !Returns a status. SAM00300
Careful. Some compilers get confused over the function name's usage. SAM00400
INTEGER N !The desired record number. SAM00500
INTEGER F !Of this file. SAM00600
CHARACTER*(*) IS !Stashed here. SAM00700
INTEGER I,L !Assistants. SAM00800
IS = "" !Clear previous content, even if null...SAM00900
IF (N.LE.0) THEN !Start on errors. SAM01000
WRITE (GETREC,1) "!No record",N !Could never be found. SAM01100
1 FORMAT (A,1X,I0) !Message, number. SAM01200
ELSE IF (F.LE.0) THEN !Obviously wrong? SAM01300
WRITE (GETREC,1) "!No unit number",F!Positive is valid. SAM01400
ELSE IF (LEN(IS).LE.0) THEN !Space awaits? SAM01500
WRITE (GETREC,1) "!String size",LEN(IS) !Nope. SAM01600
ELSE !Otherwise, there is hope. SAM01700
REWIND (F) !Clarify the file position. SAM01800
DO I = 1,N - 1 !Grind up to the desired record. SAM01900
READ (F,2,END=3) !Ignoring any content. SAM02000
END DO !Are we there yet? SAM02100
READ (F,2,END = 3) L,IS(1:MIN(L,LEN(IS))) !At last. SAM02200
2 FORMAT (Q,A) !Q = characters yet unread. SAM02300
IF (L.LT.LEN(IS)) IS(L + 1:) = "" !Clear the tail. SAM02400
IF (L.GT.LEN(IS)) THEN !Now for more silliness.SAM02500
WRITE (GETREC,1) "+Length",L !Too long to fit in IS. SAM02600
ELSE IF (L.LE.0) THEN !A zero-length record SAM02700
WRITE (GETREC,1) "+Null" !Is not the same SAM02800
ELSE IF (IS.EQ."") THEN !As a record SAM02900
WRITE (GETREC,1) "+Blank",L !Containing spaces. SAM03000
ELSE !But otherwise, SAM03100
WRITE (GETREC,1) " Length",L !Note the leading space.SAM03200
END IF !Righto, we've decided. SAM03300
END IF !And, no more options. SAM03400
RETURN !So, done. SAM03500
3 WRITE (GETREC,1) "!End on read",I !An alternative ending. SAM03600
END FUNCTION GETREC !That was interesting. SAM03700
END MODULE SAMPLER !Just a sample of possibility. SAM03800
SAM03900
PROGRAM POKE POK00100
USE SAMPLER POK00200
INTEGER ENUFF !Some sizes. POK00300
PARAMETER (ENUFF = 666) !Sufficient? POK00400
CHARACTER*(ENUFF) STUFF !Lots of memory these days. POK00500
CHARACTER*20 RESULT POK00600
INTEGER MSG,F !I/O unit numbers. POK00700
MSG = 6 !Standard output. POK00800
F = 10 !Chooose a unit number. POK00900
WRITE (MSG,*) " To select record 7 from a disc file." POK01000
POK01100
WRITE (MSG,*) "As a FORMATTED file." POK01200
OPEN (F,FILE="FileSlurpN.for",STATUS="OLD",ACTION="READ") POK01300
RESULT = GETREC(7,F,STUFF) POK01400
WRITE (MSG,1) "Result",RESULT POK01500
WRITE (MSG,1) "Record",STUFF POK01600
1 FORMAT (A,":",A) POK01700
POK01800
CLOSE (F) POK01900
WRITE (MSG,*) "As a random-access unformatted file." POK02000
OPEN (F,FILE="FileSlurpN.for",STATUS="OLD",ACTION="READ", POK02100
1 ACCESS="DIRECT",FORM="UNFORMATTED",RECL=82) !Not 80! POK02200
STUFF = "Cleared." POK02300
READ (F,REC = 7,ERR = 666) STUFF(1:80) POK02400
WRITE (MSG,1) "Record",STUFF(1:80) POK02500
STOP POK02600
666 WRITE (MSG,*) "Can't get the record!" POK02700
END !That was easy. POK02800

1
Task/Read-a-specific-line-from-a-file/Fortran/read-a-specific-line-from-a-file-2.f Normal file
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READ (F'7) STUFF(1:80)

6
Task/Read-a-specific-line-from-a-file/Fortran/read-a-specific-line-from-a-file-3.f Normal file
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@ -0,0 +1,6 @@
READ (F,REC = 7,ERR = 666, IOSTAT = IOSTAT) STUFF(1:80)
666 IF (IOSTAT.NE.0) THEN
WRITE (MSG,*) "Can't get the record: code",IOSTAT
ELSE
WRITE (MSG,1) "Record",STUFF(1:80)
END IF

25
Task/Read-a-specific-line-from-a-file/FreeBASIC/read-a-specific-line-from-a-file.basic Normal file
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@ -0,0 +1,25 @@
' FB 1.05.0 Win64
Open "input.txt" For Input As #1
Dim line_ As String
Dim count As Integer = 0
While Not Eof(1)
Line Input #1, line_ '' read each line
count += 1
If count = 7 Then
line_ = Trim(line_, Any !" \t") '' remove any leading or trailing spaces or tabs
If line_ = "" Then
Print "The 7th line is empty"
Else
Print "The 7th line is : "; line_
End If
Exit While
End If
Wend
If count < 7 Then
Print "There are only"; count; " lines in the file"
End If
Close #1
Print
Print "Press any key to quit"
Sleep

11
Task/Read-a-specific-line-from-a-file/Frink/read-a-specific-line-from-a-file.frink Normal file
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nthLine[filename, lineNum] :=
{
line = nth[lines[filenameToURL[filename]], lineNum-1]
if line != undef
return line
else
{
println["The file $filename does not contain a line number $lineNum"]
return undef
}
}

26
Task/Read-a-specific-line-from-a-file/FutureBasic/read-a-specific-line-from-a-file.basic Normal file
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@ -0,0 +1,26 @@
window 1
long i = 1
Str255 s, lineSeven
CFURLRef url
url = openpanel 1, @"Select text file"
if ( url )
open "I", 2, url
while ( not eof(2) )
line input #2, s
if ( i == 7 )
lineSeven = s : break
end if
i++
wend
close 2
if ( lineSeven[0] )
print lineSeven
else
print "File did not contain seven lines, or line was empty."
end if
end if
HandleEvents

51
Task/Read-a-specific-line-from-a-file/Go/read-a-specific-line-from-a-file.go Normal file
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package main
import (
"bufio"
"errors"
"fmt"
"io"
"os"
)
func main() {
if line, err := rsl("input.txt", 7); err == nil {
fmt.Println("7th line:")
fmt.Println(line)
} else {
fmt.Println("rsl:", err)
}
}
func rsl(fn string, n int) (string, error) {
if n < 1 {
return "", fmt.Errorf("invalid request: line %d", n)
}
f, err := os.Open(fn)
if err != nil {
return "", err
}
defer f.Close()
bf := bufio.NewReader(f)
var line string
for lnum := 0; lnum < n; lnum++ {
line, err = bf.ReadString('\n')
if err == io.EOF {
switch lnum {
case 0:
return "", errors.New("no lines in file")
case 1:
return "", errors.New("only 1 line")
default:
return "", fmt.Errorf("only %d lines", lnum)
}
}
if err != nil {
return "", err
}
}
if line == "" {
return "", fmt.Errorf("line %d empty", n)
}
return line, nil
}

7
Task/Read-a-specific-line-from-a-file/Groovy/read-a-specific-line-from-a-file.groovy Normal file
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@ -0,0 +1,7 @@
def line = null
new File("lines.txt").eachLine { currentLine, lineNumber ->
if (lineNumber == 7) {
line = currentLine
}
}
println "Line 7 = $line"

6
Task/Read-a-specific-line-from-a-file/Haskell/read-a-specific-line-from-a-file.hs Normal file
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@ -0,0 +1,6 @@
main :: IO ()
main = do contents <- readFile filename
case drop 6 $ lines contents of
[] -> error "File has less than seven lines"
l:_ -> putStrLn l
where filename = "testfile"

10
Task/Read-a-specific-line-from-a-file/Icon/read-a-specific-line-from-a-file.icon Normal file
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@ -0,0 +1,10 @@
procedure main()
write(readline("foo.bar.txt",7)|"failed")
end
procedure readline(f,n) # return n'th line of file f
f := open(\f,"r") | fail # open file
every i := n & line := |read(f) \ n do i -:= 1 # <== here
close(f)
if i = 0 then return line
end

3
Task/Read-a-specific-line-from-a-file/J/read-a-specific-line-from-a-file-1.j Normal file
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@ -0,0 +1,3 @@
readLine=: 4 :0
(x-1) {:: <;.2 ] 1!:1 boxxopen y
)

1
Task/Read-a-specific-line-from-a-file/J/read-a-specific-line-from-a-file-2.j Normal file
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@ -0,0 +1 @@
$ cal 2011 > cal.txt

2
Task/Read-a-specific-line-from-a-file/J/read-a-specific-line-from-a-file-3.j Normal file
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@ -0,0 +1,2 @@
7 readLine 'cal.txt'
9 10 11 12 13 14 15 13 14 15 16 17 18 19 13 14 15 16 17 18 19

2
Task/Read-a-specific-line-from-a-file/J/read-a-specific-line-from-a-file-4.j Normal file
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require 'files' NB. required for versions before J701
readLineT=: <:@[ {:: 'b'&freads@]

33
Task/Read-a-specific-line-from-a-file/Java/read-a-specific-line-from-a-file-1.java Normal file
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package linenbr7;
import java.io.*;
public class LineNbr7 {
public static void main(String[] args) throws Exception {
File f = new File(args[0]);
if (!f.isFile() || !f.canRead())
throw new IOException("can't read " + args[0]);
BufferedReader br = new BufferedReader(new FileReader(f));
try (LineNumberReader lnr = new LineNumberReader(br)) {
String line = null;
int lnum = 0;
while ((line = lnr.readLine()) != null
&& (lnum = lnr.getLineNumber()) < 7) {
}
switch (lnum) {
case 0:
System.out.println("the file has zero length");
break;
case 7:
boolean empty = "".equals(line);
System.out.println("line 7: " + (empty ? "empty" : line));
break;
default:
System.out.println("the file has only " + lnum + " line(s)");
}
}
}
}

20
Task/Read-a-specific-line-from-a-file/Java/read-a-specific-line-from-a-file-2.java Normal file
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@ -0,0 +1,20 @@
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
public final class ReadSpecificLineFromFile {
public static void main(String[] aArgs) throws IOException {
String fileName = "input.txt";
Path filePath = Path.of(fileName);
String seventhLine = Files.lines(filePath).skip(6).findFirst().orElse(ERROR_TOO_FEW_LINES);
String messageToUser = seventhLine.isBlank() ? ERROR_EMPTY_LINE : seventhLine;
System.out.println(messageToUser);
}
private static final String ERROR_TOO_FEW_LINES = "File has fewer than 7 lines";
private static final String ERROR_EMPTY_LINE = "Line 7 is empty";
}

7
Task/Read-a-specific-line-from-a-file/Jq/read-a-specific-line-from-a-file-1.jq Normal file
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@ -0,0 +1,7 @@
# Input - a line number to read, counting from 1
# Output - a stream with 0 or 1 items
def read_line:
. as $in
| label $top
| foreach inputs as $line
(0; .+1; if . == $in then $line, break $top else empty end) ;

4
Task/Read-a-specific-line-from-a-file/Jq/read-a-specific-line-from-a-file-2.jq Normal file
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@ -0,0 +1,4 @@
$line | tonumber
| if . > 0 then read_line
else "$line (\(.)) should be a non-negative integer"
end

2
Task/Read-a-specific-line-from-a-file/Jq/read-a-specific-line-from-a-file-3.jq Normal file
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@ -0,0 +1,2 @@
$ jq -n -r 'range(0;20) | tostring' | jq --arg line 10 -n -R -r -f Read_a_specific_line_from_a_file.jq
9

1
Task/Read-a-specific-line-from-a-file/Julia/read-a-specific-line-from-a-file-1.julia Normal file
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@ -0,0 +1 @@
open(readlines, "path/to/file")[7]

7
Task/Read-a-specific-line-from-a-file/Julia/read-a-specific-line-from-a-file-2.julia Normal file
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@ -0,0 +1,7 @@
function read_nth_lines(stream, num)
for i = 1:num-1
readline(stream)
end
result = readline(stream)
print(result != "" ? result : "No such line.")
end

2
Task/Read-a-specific-line-from-a-file/K/read-a-specific-line-from-a-file-1.k Normal file
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@ -0,0 +1,2 @@
(0:"135-0.txt")7
"will have to check the laws of the country where you are located before\r"

2
Task/Read-a-specific-line-from-a-file/K/read-a-specific-line-from-a-file-2.k Normal file
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@ -0,0 +1,2 @@
(0:"135-0.txt")7-1
"www.gutenberg.org. If you are not located in the United States, you\r"

32
Task/Read-a-specific-line-from-a-file/Kotlin/read-a-specific-line-from-a-file.kotlin Normal file
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@ -0,0 +1,32 @@
// version 1.1.2
import java.io.File
fun main(args: Array<String>) {
/* The following code reads the whole file into memory
and so should not be used for large files
which should instead be read line by line until the
desired line is reached */
val lines = File("input.txt").readLines()
if (lines.size < 7)
println("There are only ${lines.size} lines in the file")
else {
val line7 = lines[6].trim()
if (line7.isEmpty())
println("The seventh line is empty")
else
println("The seventh line is : $line7")
}
}
/* Note that 'input.txt' contains the eight lines:
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
*/

9
Task/Read-a-specific-line-from-a-file/Lasso/read-a-specific-line-from-a-file.lasso Normal file
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@ -0,0 +1,9 @@
local(f) = file('unixdict.txt')
handle => { #f->close }
local(this_line = string,line = 0)
#f->forEachLine => {
#line++
#line == 7 ? #this_line = #1
#line == 7 ? loop_abort
}
#this_line // 6th, which is the 7th line in the file

11
Task/Read-a-specific-line-from-a-file/Liberty-BASIC/read-a-specific-line-from-a-file.basic Normal file
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@ -0,0 +1,11 @@
fileName$ ="F:\sample.txt"
requiredLine =7
open fileName$ for input as #i
f$ =input$( #i, lof( #i))
close #i
line7$ =word$( f$, 7, chr$( 13))
if line7$ =chr$( 13) +chr$( 10) or line7$ ="" then notice "Empty line! ( or file has fewer lines)."
print line7$

10
Task/Read-a-specific-line-from-a-file/Lua/read-a-specific-line-from-a-file.lua Normal file
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@ -0,0 +1,10 @@
function fileLine (lineNum, fileName)
local count = 0
for line in io.lines(fileName) do
count = count + 1
if count == lineNum then return line end
end
error(fileName .. " has fewer than " .. lineNum .. " lines.")
end
print(fileLine(7, "test.txt"))

18
Task/Read-a-specific-line-from-a-file/MATLAB/read-a-specific-line-from-a-file.m Normal file
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@ -0,0 +1,18 @@
eln = 7; % extract line number 7
line = '';
fid = fopen('foobar.txt','r');
if (fid < 0)
printf('Error:could not open file\n')
else
n = 0;
while ~feof(fid),
n = n + 1;
if (n ~= eln),
fgetl(fid);
else
line = fgetl(fid);
end
end;
fclose(fid);
end;
printf('line %i: %s\n',eln,line);

10
Task/Read-a-specific-line-from-a-file/Maple/read-a-specific-line-from-a-file.maple Normal file
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@ -0,0 +1,10 @@
path := "file.txt":
specificLine := proc(path, num)
local i, input:
for i to num do
input := readline(path):
if input = 0 then break; end if:
end do:
if i = num+1 then printf("Line %d, %s", num, input):
elif i <= num then printf ("Line number %d is not reached",num): end if:
end proc:

1
Task/Read-a-specific-line-from-a-file/Mathematica/read-a-specific-line-from-a-file.math Normal file
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@ -0,0 +1 @@
If[# != EndOfFile , Print[#]]& @ ReadList["file", String, 7]

5
Task/Read-a-specific-line-from-a-file/MoonScript/read-a-specific-line-from-a-file.moon Normal file
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@ -0,0 +1,5 @@
iter = io.lines 'test.txt'
for i=0, 5
error 'Not 7 lines in file' if not iter!
print iter!

13
Task/Read-a-specific-line-from-a-file/Nanoquery/read-a-specific-line-from-a-file.nanoquery Normal file
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@ -0,0 +1,13 @@
def getline(fname, linenum)
contents = null
try
contents = new(Nanoquery.IO.File).read()
return contents[linenum]
catch
if contents = null
throw new(Exception, "unable to read from file '" + fname + "'")
else
throw new(Exception, "unable to retrieve line " + linenum + " from file: not enough lines")
end
end
end

52
Task/Read-a-specific-line-from-a-file/NetRexx/read-a-specific-line-from-a-file.netrexx Normal file
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@ -0,0 +1,52 @@
/* NetRexx */
options replace format comments java crossref symbols nobinary
parse arg inFileName lineNr .
if inFileName = '' | inFileName = '.' then inFileName = './data/input.txt'
if lineNr = '' | lineNr = '.' then lineNr = 7
do
lineTxt = readLine(inFileName, lineNr)
say '<textline number="'lineNr.right(5, 0)'">'lineTxt'</textline>'
catch ex = Exception
ex.printStackTrace()
end
return
-- =============================================================================
-- NetRexx/Java programs don't have a special mechanism to seek to a specified line number
-- the simple solution is to iterate through file. (Costly for very large files)
method readLine(inFileName, lineNr) public static signals IOException, FileNotFoundException
lineReader = LineNumberReader(FileReader(File(inFileName)))
notFound = isTrue
lineTxt = ''
loop label reading forever
line = lineReader.readLine()
select
when lineReader.getLineNumber() = lineNr then do
lineTxt = line
notFound = isFalse
leave reading -- terminate I/O loop
end
when line = null then do
leave reading -- terminate I/O loop
end
otherwise nop
end
finally
lineReader.close()
end reading
if notFound then signal RuntimeException('File' inFileName 'does not contain line' lineNr.right(5))
return lineTxt
-- =============================================================================
method isTrue() public static returns boolean
return 1 == 1
-- =============================================================================
method isFalse() public static returns boolean
return \(1 == 1)

12
Task/Read-a-specific-line-from-a-file/Nim/read-a-specific-line-from-a-file.nim Normal file
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@ -0,0 +1,12 @@
import strformat
proc readLine(f: File; num: Positive): string =
for n in 1..num:
try:
result = f.readLine()
except EOFError:
raise newException(IOError, &"Not enough lines in file; expected {num}, found {n - 1}.")
let f = open("test.txt", fmRead)
echo f.readLine(7)
f.close()

21
Task/Read-a-specific-line-from-a-file/OCaml/read-a-specific-line-from-a-file.ocaml Normal file
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@ -0,0 +1,21 @@
let input_line_opt ic =
try Some (input_line ic)
with End_of_file -> None
let nth_line n filename =
let ic = open_in filename in
let rec aux i =
match input_line_opt ic with
| Some line ->
if i = n then begin
close_in ic;
(line)
end else aux (succ i)
| None ->
close_in ic;
failwith "end of file reached"
in
aux 1
let () =
print_endline (nth_line 7 Sys.argv.(1))

6
Task/Read-a-specific-line-from-a-file/OxygenBasic/read-a-specific-line-from-a-file.basic Normal file
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@ -0,0 +1,6 @@
uses stringutil
new Textarray t
t.load "t.txt"
print t.line 7
' print t.lineCount
del t

17
Task/Read-a-specific-line-from-a-file/PHP/read-a-specific-line-from-a-file.php Normal file
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@ -0,0 +1,17 @@
<?php
$DOCROOT = $_SERVER['DOCUMENT_ROOT'];
function fileLine ($lineNum, $file) {
$count = 0;
while (!feof($file)) {
$count++;
$line = fgets($file);
if ($count == $lineNum) return $line;
}
die("Requested file has fewer than ".$lineNum." lines!");
}
@ $fp = fopen("$DOCROOT/exercises/words.txt", 'r');
if (!$fp) die("Input file not found!");
echo fileLine(7, $fp);
?>

12
Task/Read-a-specific-line-from-a-file/PL-I/read-a-specific-line-from-a-file.pli Normal file
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@ -0,0 +1,12 @@
declare text character (1000) varying, line_no fixed;
get (line_no);
on endfile (f) begin;
put skip list ('the specified line does not exist');
go to next;
end;
get file (f) edit ((text do i = 1 to line_no)) (L);
put skip list (text);
next: ;

133
Task/Read-a-specific-line-from-a-file/PL-M/read-a-specific-line-from-a-file.plm Normal file
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100H: /* READ A SPECIFIC LINE FROM A FILE */
DECLARE FALSE LITERALLY '0', TRUE LITERALLY '0FFH';
DECLARE NL$CHAR LITERALLY '0AH'; /* NEWLINE: CHAR 10 */
DECLARE EOF$CHAR LITERALLY '26'; /* EOF: CTRL-Z */
/* CP/M BDOS SYSTEM CALL, RETURNS A VALUE */
BDOS: PROCEDURE( FN, ARG )BYTE; DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END;
/* CP/M BDOS SYSTEM CALL, NO RETURN VALUE */
BDOS$P: PROCEDURE( FN, ARG ); DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END;
EXIT: PROCEDURE; CALL BDOS$P( 0, 0 ); END; /* CP/M SYSTEM RESET */
PR$CHAR: PROCEDURE( C ); DECLARE C BYTE; CALL BDOS$P( 2, C ); END;
PR$STRING: PROCEDURE( S ); DECLARE S ADDRESS; CALL BDOS$P( 9, S ); END;
PR$NL: PROCEDURE; CALL PR$STRING( .( 0DH, NL$CHAR, '$' ) ); END;
PR$NUMBER: PROCEDURE( N ); /* PRINTS A NUMBER IN THE MINIMUN FIELD WIDTH */
DECLARE N ADDRESS;
DECLARE V ADDRESS, N$STR ( 6 )BYTE, W BYTE;
V = N;
W = LAST( N$STR );
N$STR( W ) = '$';
N$STR( W := W - 1 ) = '0' + ( V MOD 10 );
DO WHILE( ( V := V / 10 ) > 0 );
N$STR( W := W - 1 ) = '0' + ( V MOD 10 );
END;
CALL PR$STRING( .N$STR( W ) );
END PR$NUMBER;
FL$EXISTS: PROCEDURE( FCB )BYTE; /* RETURNS TRUE IF THE FILE NAMED IN THE */
DECLARE FCB ADDRESS; /* FCB EXISTS */
RETURN ( BDOS( 17, FCB ) < 4 );
END FL$EXISTS ;
FL$OPEN: PROCEDURE( FCB )BYTE; /* OPEN THE FILE WITH THE SPECIFIED FCB */
DECLARE FCB ADDRESS;
RETURN ( BDOS( 15, FCB ) < 4 );
END FL$OPEN;
FL$READ: PROCEDURE( FCB )BYTE; /* READ THE NEXT RECORD FROM FCB */
DECLARE FCB ADDRESS;
RETURN ( BDOS( 20, FCB ) = 0 );
END FL$READ;
FL$CLOSE: PROCEDURE( FCB )BYTE; /* CLOSE THE FILE WITH THE SPECIFIED FCB */
DECLARE FCB ADDRESS;
RETURN ( BDOS( 16, FCB ) < 4 );
END FL$CLOSE;
PR$BYTE: PROCEDURE( B ); /* PRINT B EITHER AS A CHAR OR IN HEX */
DECLARE B BYTE;
PR$HEX: PROCEDURE( H ); /* PRINT A HEX DIGIT */
DECLARE H BYTE;
IF H < 10 THEN CALL PR$CHAR( H + '0' );
ELSE CALL PR$CHAR( ( H - 10 ) + 'A' );
END PR$HEX;
IF B >= ' ' AND B < 7FH AND B <> '$' THEN DO;
/* PRINTABLE CHAR AND NOT A $, SHOW AS A CHARACTER */
CALL PR$CHAR( B );
END;
ELSE DO;
/* NON-PRINTING CHAR OR $ - SHOW IN HEX */
CALL PR$CHAR( '$' );
CALL PR$HEX( SHR( B, 4 ) );
CALL PR$HEX( B AND 0FH );
END;
END PR$BYTE;
/* I/O USES FILE CONTROL BLOCKS CONTAINING THE FILE-NAME, POSITION, ETC. */
/* WHEN THE PROGRAM IS RUN, THE CCP WILL FIRST PARSE THE COMMAND LINE AND */
/* PUT THE FIRST PARAMETER IN FCB1, THE SECOND PARAMETER IN FCB2 */
/* BUT FCB2 OVERLAYS THE END OF FCB1 AND THE DMA BUFFER OVERLAYS THE END */
/* OF FCB2, SO WE NEED TO GET THE LINE NUMBER FROM FCB2 FIRST */
DECLARE FCB$SIZE LITERALLY '36'; /* SIZE OF A FCB */
DECLARE FCB1 LITERALLY '5CH'; /* ADDRESS OF FIRST FCB */
DECLARE FCB2 LITERALLY '6CH'; /* ADDRESS OF SECOND FCB */
DECLARE DMA$BUFFER LITERALLY '80H'; /* DEFAULT DMA BUFFER ADDRESS */
DECLARE DMA$SIZE LITERALLY '128'; /* SIZE OF THE DMA BUFFER */
DECLARE F$PTR ADDRESS, F$CHAR BASED F$PTR BYTE;
/* GET THE LINE NUMBER FROM THE SECOND PARAMETER */
DECLARE LINE$NUMBER ADDRESS;
LINE$NUMBER = 0;
DO F$PTR = FCB2 + 1 TO FCB2 + 8;
IF F$CHAR >= '0' AND F$CHAR <= '9' THEN DO;
LINE$NUMBER = ( LINE$NUMBER * 10 ) + ( F$CHAR - '0' );
END;
END;
/* CLEAR THE PARTS OF FCB1 OVERLAYED BY FCB2 */
DO F$PTR = FCB1 + 12 TO FCB1 + ( FCB$SIZE - 1 );
F$CHAR = 0;
END;
/* SHOW THE REQUIRED LINE FROM THE FILE, IF THE FILE AND LINE EXIST */
IF NOT FL$EXISTS( FCB1 ) THEN DO; /* THE FILE DOES NOT EXIST */
CALL PR$STRING( .'FILE NOT FOUND$' );CALL PR$NL;
END;
ELSE IF NOT FL$OPEN( FCB1 ) THEN DO; /* UNABLE TO OPEN THE FILE */
CALL PR$STRING( .'UNABLE TO OPEN THE FILE$' );CALL PR$NL;
END;
ELSE DO; /* FILE EXISTS AND OPENED OK - ATTEMPT TO FIND THE LINE */
DECLARE LN ADDRESS, GOT$RCD BYTE, GOT$LINE BYTE, DMA$END ADDRESS;
DMA$END = DMA$BUFFER + ( DMA$SIZE - 1 );
GOT$RCD = FL$READ( FCB1 ); /* GET THE FIRST RECORD */
GOT$LINE = FALSE;
F$PTR = DMA$BUFFER;
LN = 1;
CALL PR$NUMBER( LINE$NUMBER ); CALL PR$STRING( .': <$' );
DO WHILE( GOT$RCD AND LN <= LINE$NUMBER );
IF F$PTR > DMA$END THEN DO;
/* AT THE END OF THE BUFFER - GET THE NEXT RECORD */
GOT$RCD = FL$READ( FCB1 );
F$PTR = DMA$BUFFER;
END;
ELSE IF F$CHAR = NL$CHAR THEN DO; /* END OF LINE */
LN = LN + 1;
IF LN = LINE$NUMBER THEN GOT$LINE = TRUE;
END;
ELSE IF F$CHAR = EOF$CHAR THEN GOT$RCD = FALSE; /* END OF FILE */
ELSE IF LN = LINE$NUMBER THEN CALL PR$BYTE( F$CHAR );
F$PTR = F$PTR + 1;
END;
CALL PR$CHAR( '>' ); CALL PR$NL;
/* SHOULD NOW HAVE EOF OR THE END OF THE REQUIRED LINE */
IF NOT GOT$LINE THEN DO;
/* COULDN'T READ THE SPECIFIED LINE */
CALL PR$STRING( .'CANNOT READ LINE $' );
CALL PR$NUMBER( LINE$NUMBER );
END;
/* CLOSE THE FILE */
IF NOT FL$CLOSE( FCB1 ) THEN DO;
CALL PR$STRING( .'UNABLE TO CLOSE THE FILE$' ); CALL PR$NL;
END;
END;
CALL EXIT;
EOF

38
Task/Read-a-specific-line-from-a-file/Pascal/read-a-specific-line-from-a-file.pas Normal file
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Program FileTruncate;
uses
SysUtils;
const
filename = 'test';
position = 7;
var
myfile: text;
line: string;
counter: integer;
begin
if not FileExists(filename) then
begin
writeln('Error: File does not exist.');
exit;
end;
Assign(myfile, filename);
Reset(myfile);
counter := 0;
Repeat
if eof(myfile) then
begin
writeln('Error: The file "', filename, '" is too short. Cannot read line ', position);
Close(myfile);
exit;
end;
inc(counter);
readln(myfile);
until counter = position - 1;
readln(myfile, line);
Close(myfile);
writeln(line);
end.

4
Task/Read-a-specific-line-from-a-file/Perl/read-a-specific-line-from-a-file.pl Normal file
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#!/usr/bin/perl -s
# invoke as <scriptname> -n=7 [input]
while (<>) { $. == $n and print, exit }
die "file too short\n";

8
Task/Read-a-specific-line-from-a-file/Phix/read-a-specific-line-from-a-file-1.phix Normal file
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@ -0,0 +1,8 @@
-->
<span style="color: #004080;">object</span> <span style="color: #000000;">lines</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">get_text</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"TEST.TXT"</span><span style="color: #0000FF;">,</span><span style="color: #004600;">GT_LF_STRIPPED</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #004080;">sequence</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lines</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">and</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lines</span><span style="color: #0000FF;">)>=</span><span style="color: #000000;">7</span> <span style="color: #008080;">then</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">lines</span><span style="color: #0000FF;">[</span><span style="color: #000000;">7</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">else</span>
<span style="color: #0000FF;">?</span><span style="color: #008000;">"no line 7"</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<!--

8
Task/Read-a-specific-line-from-a-file/Phix/read-a-specific-line-from-a-file-2.phix Normal file
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@ -0,0 +1,8 @@
-->
<span style="color: #004080;">integer</span> <span style="color: #000000;">fn</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">open</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"TEST.TXT"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"r"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">6</span> <span style="color: #008080;">do</span>
<span style="color: #0000FF;">{}</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">gets</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #0000FF;">?</span><span style="color: #7060A8;">gets</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span> <span style="color: #000080;font-style:italic;">-- (shows -1 if past eof)</span>
<span style="color: #7060A8;">close</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<!--

8
Task/Read-a-specific-line-from-a-file/Phixmonti/read-a-specific-line-from-a-file.phixmonti Normal file
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@ -0,0 +1,8 @@
include ..\Utilitys.pmt
argument 1 get "r" fopen var f drop
0
7 for
f fgets number? if f fclose exitfor else nip nip endif
endfor
print /# show -1 if past eof #/

3
Task/Read-a-specific-line-from-a-file/PicoLisp/read-a-specific-line-from-a-file.l Normal file
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@ -0,0 +1,3 @@
(in "file.txt"
(do 6 (line))
(or (line) (quit "No 7 lines")) )

7
Task/Read-a-specific-line-from-a-file/PowerShell/read-a-specific-line-from-a-file.psh Normal file
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@ -0,0 +1,7 @@
$file = Get-Content c:\file.txt
if ($file.count -lt 7)
{Write-Warning "The file is too short!"}
else
{
$file | Where Readcount -eq 7 | set-variable -name Line7
}

32
Task/Read-a-specific-line-from-a-file/PureBasic/read-a-specific-line-from-a-file.basic Normal file
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Structure lineLastRead
lineRead.i
line.s
EndStructure
Procedure readNthLine(file, n, *results.lineLastRead)
*results\lineRead = 0
While *results\lineRead < n And Not Eof(file)
*results\line = ReadString(file)
*results\lineRead + 1
Wend
If *results\lineRead = n
ProcedureReturn 1
EndIf
EndProcedure
Define filename.s = OpenFileRequester("Choose file to read a line from", "*.*", "All files (*.*)|*.*", 0)
If filename
Define file = ReadFile(#PB_Any, filename)
If file
Define fileReadResults.lineLastRead, lineToRead = 7
If readNthLine(file, lineToRead, fileReadResults)
MessageRequester("Results", fileReadResults\line)
Else
MessageRequester("Error", "There are less than " + Str(lineToRead) + " lines in file.")
EndIf
CloseFile(file)
Else
MessageRequester("Error", "Couldn't open file " + filename + ".")
EndIf
EndIf

7
Task/Read-a-specific-line-from-a-file/Python/read-a-specific-line-from-a-file-1.py Normal file
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@ -0,0 +1,7 @@
with open('xxx.txt') as f:
for i, line in enumerate(f):
if i == 6:
break
else:
print('Not 7 lines in file')
line = None

7
Task/Read-a-specific-line-from-a-file/Python/read-a-specific-line-from-a-file-2.py Normal file
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@ -0,0 +1,7 @@
from itertools import islice
with open('xxx.txt') as f:
try:
line = next(islice(f, 6, 7))
except StopIteration:
print('Not 7 lines in file')

1
Task/Read-a-specific-line-from-a-file/Python/read-a-specific-line-from-a-file-3.py Normal file
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@ -0,0 +1 @@
print open('xxx.txt').readlines()[:7][-1]

15
Task/Read-a-specific-line-from-a-file/QBasic/read-a-specific-line-from-a-file.basic Normal file
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@ -0,0 +1,15 @@
f = FREEFILE
OPEN "input.txt" FOR INPUT AS #f
lineapedida = 7
cont = 0
DO WHILE NOT EOF(f)
LINE INPUT #f, linea$
cont = cont + 1
IF cont = lineapedida THEN
IF linea$ = "" THEN PRINT "The 7th line is empty" ELSE PRINT linea$
EXIT DO
END IF
LOOP
IF cont < lineapedida THEN PRINT "There are only "; cont; " lines in the file"
CLOSE #1

4
Task/Read-a-specific-line-from-a-file/R/read-a-specific-line-from-a-file.r Normal file
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@ -0,0 +1,4 @@
> seven <- scan('hw.txt', '', skip = 6, nlines = 1, sep = '\n') # too short
Read 0 items
> seven <- scan('Incoming/quotes.txt', '', skip = 6, nlines = 1, sep = '\n')
Read 1 item

2
Task/Read-a-specific-line-from-a-file/REBOL/read-a-specific-line-from-a-file.rebol Normal file
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@ -0,0 +1,2 @@
x: pick read/lines request-file/only 7
either x [print x] [print "No seventh line"]

18
Task/Read-a-specific-line-from-a-file/REXX/read-a-specific-line-from-a-file-1.rexx Normal file
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/*REXX program reads a specific line from a file (and displays the length and content).*/
parse arg FID n . /*obtain optional arguments from the CL*/
if FID=='' | FID=="," then FID= 'JUNK.TXT' /*not specified? Then use the default.*/
if n=='' | n=="," then n=7 /* " " " " " " */
if lines(FID)==0 then call ser "wasn't found." /*see if the file exists (or not). */
call linein FID, n-1 /*read the record previous to N. */
if lines(FID)==0 then call ser "doesn't contain" N 'lines.'
/* [↑] any more lines to read in file?*/
$=linein(FID) /*read the Nth record in the file. */
say 'File ' FID " line " N ' has a length of: ' length($)
say 'File ' FID " line " N 'contents: ' $ /*display the contents of the Nth line.*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
ser: say; say '***error!*** File ' FID " " arg(1); say; exit 13

21
Task/Read-a-specific-line-from-a-file/REXX/read-a-specific-line-from-a-file-2.rexx Normal file
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@ -0,0 +1,21 @@
/*REXX program reads a specific line from a file (and displays the length and content).*/
parse arg FID n . /*obtain optional arguments from the CL*/
if FID=='' | FID=="," then FID= 'JUNK.TXT' /*not specified? Then use the default.*/
if n=='' | n=="," then n=7 /* " " " " " " */
if lines(FID)==0 then call ser "wasn't found." /*see if the file exists (or not). */
do n-1
call linein FID /*read all the lines previous to N. */
end /*n-1*/
if lines(FID)==0 then call ser "doesn't contain" N 'lines.'
/* [↑] any more lines to read in file?*/
$=linein(FID) /*read the Nth record in the file. */
say 'File ' FID " line " N ' has a length of: ' length($)
say 'File ' FID " line " N 'contents: ' $ /*display the contents of the Nth line.*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
ser: say; say '***error!*** File ' FID " " arg(1); say; exit 13

9
Task/Read-a-specific-line-from-a-file/Racket/read-a-specific-line-from-a-file.rkt Normal file
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@ -0,0 +1,9 @@
#lang racket
;; simple, but reads the whole file
(define s1 (list-ref (file->lines "some-file") 6))
;; more efficient: read and discard n-1 lines
(define s2
(call-with-input-file "some-file"
(λ(i) (for/last ([line (in-lines i)] [n 7]) line))))

1
Task/Read-a-specific-line-from-a-file/Raku/read-a-specific-line-from-a-file.raku Normal file
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@ -0,0 +1 @@
say lines[6] // die "Short file";

7
Task/Read-a-specific-line-from-a-file/Red/read-a-specific-line-from-a-file.red Normal file
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@ -0,0 +1,7 @@
>> x: pick read/lines %file.txt 7
case [
x = none [print "File has less than seven lines"]
(length? x) = 0 [print "Line 7 is empty"]
(length? x) > 0 [print append "Line seven = " x]
]

12
Task/Read-a-specific-line-from-a-file/Ring/read-a-specific-line-from-a-file.ring Normal file
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@ -0,0 +1,12 @@
fp = fopen("C:\Ring\ReadMe.txt","r")
n = 0
r = ""
while isstring(r)
while n < 8
r = fgetc(fp)
if r = char(10) n++ see nl
else see r ok
end
end
fclose(fp)

1
Task/Read-a-specific-line-from-a-file/Ruby/read-a-specific-line-from-a-file.rb Normal file
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@ -0,0 +1 @@
seventh_line = open("/etc/passwd").each_line.take(7).last

10
Task/Read-a-specific-line-from-a-file/Run-BASIC/read-a-specific-line-from-a-file.basic Normal file
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@ -0,0 +1,10 @@
fileName$ = "f:\sample.txt"
requiredLine = 7
open fileName$ for input as #f
for i = 1 to requiredLine
if not(eof(#f)) then line input #f, a$
next i
close #f
print a$
end

19
Task/Read-a-specific-line-from-a-file/Rust/read-a-specific-line-from-a-file-1.rust Normal file
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@ -0,0 +1,19 @@
use std::fs::File;
use std::io::BufRead;
use std::io::BufReader;
use std::io::Error;
use std::path::Path;
fn main() {
let path = Path::new("file.txt");
let line_num = 7usize;
let line = get_line_at(&path, line_num - 1);
println!("{}", line.unwrap());
}
fn get_line_at(path: &Path, line_num: usize) -> Result<String, Error> {
let file = File::open(path).expect("File not found or cannot be opened");
let content = BufReader::new(&file);
let mut lines = content.lines();
lines.nth(line_num).expect("No line found at that position")
}

32
Task/Read-a-specific-line-from-a-file/Rust/read-a-specific-line-from-a-file-2.rust Normal file
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@ -0,0 +1,32 @@
use std::env;
use std::fs::File;
use std::io::BufRead;
use std::io::BufReader;
use std::path::Path;
fn main() {
if env::args().len() <= 1 {
println!("At least a path to a file is needed: No file path given");
return;
} else {
let path = &env::args().nth(1).expect("could not parse the path");
let path = Path::new(&path);
let mut line_num = 1usize;
if let Some(arg) = env::args().nth(2) {
line_num = arg.parse::<usize>().expect("Parsing line number failed");
}
print_line_at(&path, line_num);
}
}
fn print_line_at(path: &Path, line_num: usize) {
if line_num < 1 {
panic!("Line number has to be > 0");
}
let line_num = line_num - 1;
let file = File::open(path).expect("File not found or cannot be opened");
let content = BufReader::new(&file);
let mut lines = content.lines();
let line = lines.nth(line_num).expect("No line found at given position");
println!("{}", line.expect("None line"));
}

7
Task/Read-a-specific-line-from-a-file/SPL/read-a-specific-line-from-a-file.spl Normal file
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@ -0,0 +1,7 @@
lines = #.readlines("test.txt")
#.output("Seventh line of text:")
? #.size(lines,1)<7
#.output("is absent")
!
#.output(lines[7])
.

2
Task/Read-a-specific-line-from-a-file/Scala/read-a-specific-line-from-a-file-1.scala Normal file
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@ -0,0 +1,2 @@
val lines = io.Source.fromFile("input.txt").getLines
val seventhLine = lines drop(6) next

13
Task/Read-a-specific-line-from-a-file/Scala/read-a-specific-line-from-a-file-2.scala Normal file
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@ -0,0 +1,13 @@
var lines: Iterator[String] = _
try {
lines = io.Source.fromFile("input.txt").getLines drop(6)
} catch {
case exc: java.io.IOException =>
println("File not found")
}
var seventhLine: String = _
if (lines != null) {
if (lines.isEmpty) println("too few lines in file")
else seventhLine = lines next
}
if ("" == seventhLine) println("line is empty")

6
Task/Read-a-specific-line-from-a-file/Scala/read-a-specific-line-from-a-file-3.scala Normal file
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@ -0,0 +1,6 @@
val file = try Left(io.Source.fromFile("input.txt")) catch {
case exc => Right(exc.getMessage)
}
val seventhLine = (for(f <- file.left;
line <- f.getLines.toStream.drop(6).headOption.toLeft("too few lines").left) yield
if (line == "") Right("line is empty") else Left(line)).joinLeft

1
Task/Read-a-specific-line-from-a-file/Sed/read-a-specific-line-from-a-file-1.sed Normal file
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@ -0,0 +1 @@
sed -n 7p

1
Task/Read-a-specific-line-from-a-file/Sed/read-a-specific-line-from-a-file-2.sed Normal file
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@ -0,0 +1 @@
sed '7h;$!d;x;s/^$/Error: no such line/'

32
Task/Read-a-specific-line-from-a-file/Seed7/read-a-specific-line-from-a-file.seed7 Normal file
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@ -0,0 +1,32 @@
$ include "seed7_05.s7i";
const func string: getLine (inout file: aFile, in var integer: lineNum) is func
result
var string: line is "";
begin
while lineNum > 1 and hasNext(aFile) do
readln(aFile);
decr(lineNum);
end while;
line := getln(aFile);
end func;
const proc: main is func
local
var string: fileName is "input.txt";
var file: aFile is STD_NULL;
var string: line is "";
begin
aFile := open(fileName, "r");
if aFile = STD_NULL then
writeln("Cannot open " <& fileName);
else
line := getLine(aFile, 7);
if eof(aFile) then
writeln("The file does not have 7 lines");
else
writeln("The 7th line of the file is:");
writeln(line);
end if;
end if;
end func;

1
Task/Read-a-specific-line-from-a-file/SenseTalk/read-a-specific-line-from-a-file.sensetalk Normal file
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@ -0,0 +1 @@
put line 7 of file "example.txt" into theLine

11
Task/Read-a-specific-line-from-a-file/Sidef/read-a-specific-line-from-a-file.sidef Normal file
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@ -0,0 +1,11 @@
func getNthLine(filename, n) {
var file = File.new(filename);
file.open_r.each { |line|
Num($.) == n && return line;
}
warn "file #{file} does not have #{n} lines, only #{$.}\n";
return nil;
}
var line = getNthLine("/etc/passwd", 7);
print line if defined line;

1
Task/Read-a-specific-line-from-a-file/Smalltalk/read-a-specific-line-from-a-file.st Normal file
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@ -0,0 +1 @@
line := (StandardFileStream oldFileNamed: 'test.txt') contents lineNumber: 7.

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