June 2018 Update

Task/Read-a-specific-line-from-a-file/Aime/read-a-specific-line-from-a-file.aime

@@ -3,28 +3,24 @@ read_line(text &line, text path, integer n)
 {
     file f;
 
-    f_affix(f, path);
+    f.affix(path);
 
-    while (n) {
-	n -= 1;
-	f_slip(f);
-    }
+    call_n(n, f_slip, f);
 
-    f_line(f, line);
+    f.line(line);
 }
 
 
 integer
 main(void)
 {
-    if (2 < argc()) {
-	text line;
+    if (1 < argc()) {
+        text line;
 
-	read_line(line, argv(1), 6);
+        read_line(line, argv(1), 6);
 
-	o_text(line);
-	o_byte('\n');
+        o_("7th line is:\n", line, "\n");
     }
 
-    return 0;
+    0;
 }

Task/Read-a-specific-line-from-a-file/Red/read-a-specific-line-from-a-file.red

@@ -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]
+]

Task/Read-a-specific-line-from-a-file/Rust/read-a-specific-line-from-a-file-1.rust

@@ -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")
+}

Task/Read-a-specific-line-from-a-file/Rust/read-a-specific-line-from-a-file-2.rust

@@ -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"));
+}