A-M baby

Task/Flow-control-structures/0DESCRIPTION

@@ -0,0 +1,2 @@
+{{Control Structures}}
+In this task, we document common flow-control structures. One common example of a flow-control structure is the <tt>goto</tt> construct. Note that [[Conditional Structures]] and [[Iteration|Loop Structures]] have their own articles/categories.

Task/Flow-control-structures/1META.yaml

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+---
+note: Control Structures

Task/Flow-control-structures/6502-Assembly/flow-control-structures-1.6502

@@ -0,0 +1,2 @@
+		JMP $8000		;immediately JuMP to $8000 and begin executing
+					;instructions there.

Task/Flow-control-structures/6502-Assembly/flow-control-structures-2.6502

@@ -0,0 +1,2 @@
+		JMP ($8000)		;immediately JuMP to the address in memory locations
+					;$8000 and $8001

Task/Flow-control-structures/6502-Assembly/flow-control-structures-3.6502

@@ -0,0 +1 @@
+		JSR $8000	;Jump to SubRoutine

Task/Flow-control-structures/6502-Assembly/flow-control-structures-4.6502

@@ -0,0 +1 @@
+		RTS		;ReTurn from Subroutine

Task/Flow-control-structures/6502-Assembly/flow-control-structures-5.6502

@@ -0,0 +1 @@
+		BRK		;BReaK

Task/Flow-control-structures/6502-Assembly/flow-control-structures-6.6502

@@ -0,0 +1 @@
+		RTI		;ReTurn from Interrupt

Task/Flow-control-structures/ALGOL-68/flow-control-structures-1.alg

@@ -0,0 +1,12 @@
+(
+   FOR j TO 1000 DO
+     FOR i TO j-1 DO
+       IF random > 0.999 THEN
+         printf(($"Exited when: i="g(0)", j="g(0)l$,i,j));
+         done
+       FI
+       # etc. #
+     OD
+   OD;
+ done: EMPTY
+);

Task/Flow-control-structures/ALGOL-68/flow-control-structures-2.alg

@@ -0,0 +1,12 @@
+STRING medal = (
+  []PROC VOID award = (gold,silver,bronze);
+
+  award[ 1 + ENTIER (random*3)];
+
+  gold: "Gold" EXIT
+  silver: "Silver" EXIT
+  bronze: "Bronze"
+
+);
+
+print(("Medal awarded: ",medal, new line));

Task/Flow-control-structures/ALGOL-68/flow-control-structures-3.alg

@@ -0,0 +1,21 @@
+STRING final state = (
+  INT condition;
+  PROC do something = VOID: condition := 1 + ENTIER (3 * random);
+
+  state1:
+     do something;
+     CASE condition IN
+        state 1, state 2
+     OUT
+        state n
+     ESAC
+  EXIT
+
+  state 2:
+     "State Two"
+  EXIT
+
+  state n:
+     "State N"
+);
+print(("Final state: ",final state, new line));

Task/Flow-control-structures/ALGOL-68/flow-control-structures-4.alg

@@ -0,0 +1,22 @@
+# example from: http://www.xs4all.nl/~jmvdveer/algol.html - GPL #
+determine first generation;
+WHILE can represent next generation
+DO calculate next generation;
+   print next generation
+OD.
+
+determine first generation:
+   INT previous := 1, current := 3.
+
+can represent next generation:
+   current <= max int - previous.
+
+calculate next generation:
+   INT new = current + previous;
+   previous := current;
+   current := new.
+
+print next generation:
+   printf (($lz","3z","3z","2z-d$, current,
+            $xz","3z","3z","2z-d$, previous,
+            $xd.n(real width - 1)d$, current / previous)).

Task/Flow-control-structures/AWK/flow-control-structures.awk

@@ -0,0 +1,5 @@
+$ awk 'BEGIN{for(i=1;;i++){if(i%2)continue; if(i>=10)break; print i}}'
+2
+4
+6
+8

Task/Flow-control-structures/Ada/flow-control-structures-1.ada

@@ -0,0 +1,3 @@
+<<Top>>
+   Put_Line("Hello, World");
+   goto Top;

Task/Flow-control-structures/Ada/flow-control-structures-2.ada

@@ -0,0 +1,8 @@
+Outer:
+   loop
+      -- do something
+      loop
+         -- do something else
+         exit Outer; -- exits both the inner and outer loops
+      end loop;
+   end loop;

Task/Flow-control-structures/Ada/flow-control-structures-3.ada

@@ -0,0 +1,7 @@
+select
+   delay 10.0;
+   Put_Line ("Cannot finish this in 10s");
+then abort
+   -- do some lengthy calculation
+   ...
+end select;

Task/Flow-control-structures/AutoHotkey/flow-control-structures.ahk

@@ -0,0 +1,14 @@
+MsgBox, calling Label1
+Gosub, Label1
+MsgBox, Label1 subroutine finished
+Goto Label2
+MsgBox, calling Label2 ; this part is never reached
+Return
+
+Label1:
+  MsgBox, Label1
+Return
+
+Label2:
+  MsgBox, Label2 will not return to calling routine
+Return

Task/Flow-control-structures/BBC-BASIC/flow-control-structures.bbc

@@ -0,0 +1,11 @@
+      GOSUB subroutine
+
+      (loop)
+      PRINT "Infinite loop"
+      GOTO loop
+      END
+
+      (subroutine)
+      PRINT "In subroutine"
+      WAIT 100
+      RETURN

Task/Flow-control-structures/C++/flow-control-structures-1.cpp

@@ -0,0 +1,8 @@
+#include <iostream>
+
+int main()
+{
+ LOOP:
+  std::cout << "Hello, World!\n";
+ goto LOOP;
+}

Task/Flow-control-structures/C++/flow-control-structures-2.cpp

@@ -0,0 +1,71 @@
+#include <iostream>
+#include <ostream>
+
+void foo()
+{
+  std::cout << "Going to throw an exception.\n";
+  throw 7; // almost any object can be thrown, including ints
+  std::throw << "This output will never execute.\n";
+}
+
+void bar()
+{
+  std::cout << "Going to call foo().\n";
+  foo();
+  std::cout << "This will be skipped by the exception coming from foo.\n";
+}
+
+void baz()
+{
+  try // everything thrown from inside the following code block
+  {   // will be covered by the following catch clauses
+    std::cout << "Going to call bar().\n";
+    bar();
+    std::cout << "This will be skipped by the exception coming from foo.\n";
+  }
+  catch(...) // a simple catch-all, but doesn't give access to the thrown exception
+  {
+    std::cout << "An exception occured. I'll just throw it on.\n";
+    throw; // without an argument, the caught exception is re-thrown
+  }
+  std::cout << "This will not be executed due to the re-throw in the catch block\n";
+}
+
+void foobar()
+{
+  try
+  {
+    baz();
+  }
+  catch(char const* s)
+  {
+    std::cout << "If foo had thrown a char const*, this code would be executed.\n";
+    std::cout << "In that case, the thrown char const* would read " << s << ".\n";
+  }
+  catch(int i)
+  {
+    std::cout << "Caught an int, with value " << i << " (should be 7).\n";
+    std::cout << "Not rethrowing the int.\n";
+  }
+  catch(...)
+  {
+    std::cout << "This catch-all doesn't get invoked because the catch(int) above\n"
+              << "already took care of the exception (even if it had rethrown the\n"
+              << "exception, this catch-all would not be invoked, because it's\n"
+              << "only invoked for exceptions coming from the try block.\n";
+  }
+  std::cout << "This will be executed, since the exception was handled above, and not rethrown.\n";
+}
+
+int main()
+{
+  try
+  {
+    foobar();
+  }
+  catch(...)
+  {
+    std::cout << "The main function never sees the exception, because it's completely handled\n"
+              << "inside foobar(). Thus this catch-all block never gets invoked.\n";
+  }
+}

Task/Flow-control-structures/C/flow-control-structures.c

@@ -0,0 +1,13 @@
+int main()
+{
+  int i,j;
+  for (j=1; j<1000; j++) {
+    for (i=0; i<j, i++) {
+      if (exit_early())
+        goto out;
+      /* etc. */
+    }
+  }
+out:
+  return 0;
+}

Task/Flow-control-structures/D/flow-control-structures-1.d

@@ -0,0 +1,7 @@
+import std.stdio;
+
+void main() {
+    label1:
+    writeln("I'm in your infinite loop.");
+    goto label1;
+}

Task/Flow-control-structures/D/flow-control-structures-2.d

@@ -0,0 +1,22 @@
+import std.stdio;
+
+class DerivedException : Exception {
+    this(string msg) { super(msg); }
+}
+
+void main(string[] args) {
+    try {
+        if (args[1] == "throw")
+            throw new Exception("message");
+    } catch (DerivedException ex) {
+        // We never threw a DerivedException, so this
+        // block is never called.
+        writefln("caught derived exception %s", ex);
+    } catch (Exception ex) {
+        writefln("caught exception: %s", ex);
+    } catch (Throwable ex) {
+        writefln("caught throwable: %s", ex);
+    } finally {
+        writeln("finished (exception or none).");
+    }
+}

Task/Flow-control-structures/D/flow-control-structures-3.d

@@ -0,0 +1,13 @@
+import std.stdio;
+
+void main(string[] args) {
+    scope(exit)
+        writeln("Gone");
+
+    if (args[1] == "throw")
+        throw new Exception("message");
+
+    scope(exit)
+        writeln("Gone, but we passed the first" ~
+                " chance to throw an exception.");
+}

Task/Flow-control-structures/Forth/flow-control-structures.fth

@@ -0,0 +1,13 @@
+: checked-array
+  CREATE ( size -- ) DUP , CELLS ALLOT
+  DOES> ( i -- a+i )
+    2DUP @ 0 SWAP WITHIN IF
+      SWAP 1+ CELLS +
+    ELSE
+      1 THROW
+    THEN ;
+
+8 checked-array myarray
+
+: safe-access ( i -- a[i] )
+  ['] myarray CATCH 1 = IF ." Out of bounds!" 0 THEN ;

Task/Flow-control-structures/GW-BASIC/flow-control-structures.bas

@@ -0,0 +1,7 @@
+10 LET a=1
+20 IF a=2 THEN PRINT "This is a conditional statement"
+30 IF a=1 THEN GOTO 50: REM a conditional jump
+40 PRINT "This statement will be skipped"
+50 PRINT ("Hello" AND (1=2)): REM This does not print
+100 PRINT "Endless loop"
+110 GOTO 100:REM an unconditional jump

Task/Flow-control-structures/Go/flow-control-structures-1.go

@@ -0,0 +1,4 @@
+func main() {
+inf:
+    goto inf
+}

Task/Flow-control-structures/Go/flow-control-structures-2.go

@@ -0,0 +1,18 @@
+import "os"
+
+func processFile() {
+    f, err := os.Open("file")
+    if err != nil {
+        // (probably do something with the error)
+        return // no need to close file, it didn't open
+    }
+    defer f.Close() // file is open.  no matter what, close it on return
+    var lucky bool
+    // some processing
+    if (lucky) {
+        // f.Close() will get called here
+        return
+    }
+    // more processing
+    // f.Close() will get called here too
+}

Task/Flow-control-structures/Go/flow-control-structures-3.go

@@ -0,0 +1,16 @@
+package main
+
+import "fmt"
+
+func printOnes() {
+    for {
+        fmt.Println("1")
+    }
+}
+
+func main() {
+    go printOnes()
+    for {
+        fmt.Println("0")
+    }
+}

Task/Flow-control-structures/Go/flow-control-structures-4.go

@@ -0,0 +1,8 @@
+func answer(phone1, phone2 chan int) {
+    select {
+    case <-phone1:
+        // talk on phone one
+    case <-phone2:
+        // talk on phone two
+    }
+}

Task/Flow-control-structures/Haskell/flow-control-structures.hs

@@ -0,0 +1,12 @@
+import Control.Monad
+import Control.Monad.Trans
+import Control.Monad.Exit
+
+main = do
+    runExitTMaybe $ do
+        forM_ [1..5] $ \x -> do
+            forM_ [1..5] $ \y -> do
+                lift $ print (x, y)
+                when (x == 3 && y == 2) $
+                    exitWith ()
+    putStrLn "Done."

Task/Flow-control-structures/HicEst/flow-control-structures.hicest

@@ -0,0 +1,17 @@
+1 GOTO 2 ! branch to label
+
+2 READ(FIle=name, IOStat=ios, ERror=3) something ! on error branch to label 3
+
+3 ALARM(delay, n) ! n=2...9 simulate F2 to F9 keys: call asynchronously "Alarm"-SUBROUTINES F2...F9 with a delay
+
+4 ALARM(  1  ) ! lets HicEst wait at this statement for any keyboard or mouse event
+
+5 SYSTEM(WAIT=1000) ! msec
+
+6 XEQ('CALL my_subroutine', *7) ! executes command string, on error branch to label 7
+
+7 y = EXP(1E100, *8) ! on error branch to label 8
+
+8 y = LOG( 0 , *9)   ! on error branch to label 9
+
+9 ALARM( 999 ) ! quit HicEst immediately

Task/Flow-control-structures/IDL/flow-control-structures-1.idl

@@ -0,0 +1,3 @@
+test:
+..some code here
+goto, test

Task/Flow-control-structures/IDL/flow-control-structures-2.idl

@@ -0,0 +1 @@
+on_error, test

Task/Flow-control-structures/IDL/flow-control-structures-3.idl

@@ -0,0 +1 @@
+on_ioerror, test

Task/Flow-control-structures/IDL/flow-control-structures-4.idl

@@ -0,0 +1 @@
+break

Task/Flow-control-structures/IDL/flow-control-structures-5.idl

@@ -0,0 +1 @@
+continue

Task/Flow-control-structures/Icon/flow-control-structures-1.icon

@@ -0,0 +1,9 @@
+    if x := every i := 1 to *container do {     # * is the 'length' operator
+        if container[i] ~== y then
+            write("item ", i, " is not interesting")
+        else
+            break a
+    } then
+        write("found item ", x)
+    else
+        write("did not find an item")

Task/Flow-control-structures/Icon/flow-control-structures-2.icon

@@ -0,0 +1 @@
+    break break next

Task/Flow-control-structures/Icon/flow-control-structures-3.icon

@@ -0,0 +1 @@
+    x := ftn()

Task/Flow-control-structures/Icon/flow-control-structures-4.icon

@@ -0,0 +1,8 @@
+    &error := 1
+    mayErrorOut()
+    if &error == 1 then
+        &error := 0     # clear the trap
+    else {
+        # deal with the fault
+        handleError(&errornumber, &errortext, &errorvalue)   # keyword values containing facts about the failure
+    }

Task/Flow-control-structures/Icon/flow-control-structures-5.icon

@@ -0,0 +1 @@
+    runerr(errnumber, errorvalue)    # choose an error number and supply the offending value

Task/Flow-control-structures/J/flow-control-structures.j

@@ -0,0 +1,2 @@
+   2 * 1 2 3
+2 4 6

Task/Flow-control-structures/Java/flow-control-structures-1.java

@@ -0,0 +1,33 @@
+switch (xx) {
+  case 1:
+  case 2:
+    /* 1 & 2 both come here... */
+    ...
+    break;
+  case 4:
+    /* 4 comes here... */
+    ...
+    break;
+  case 5:
+    /* 5 comes here... */
+    ...
+    break;
+  default:
+    /* everything else */
+    break;
+}
+
+for (int i = 0; i < 10; ++i) {
+  ...
+  if (some_condition) { break; }
+  ...
+}
+
+_Time_: do {
+  for (int i = 0; i < 10; ++i) {
+    ...
+    if (some_condition) { break _Time_; /* terminate the do-while loop */}
+    ...
+    }
+  ...
+} while (thisCondition);

Task/Flow-control-structures/Java/flow-control-structures-2.java

@@ -0,0 +1,25 @@
+while (condition) {
+  ...
+  if (someCondition) { continue; /* skip to beginning of this loop */ }
+  ...
+}
+
+top: for (int 1 = 0; i < 10; ++i) {
+  ...
+  middle: for (int j = 0; j < 10; ++j) {
+    ...
+    bottom: for (int k = 0; k < 10; ++k) {
+    ...
+    if (top_condition) { continue top; /* restart outer loop */ }
+    ...
+    if (middle_condition) { continue middle; /* restart middle loop */ }
+    ...
+    if (bottom_condition) { continue bottom; /* restart bottom loop */ }
+    ...
+    if (bottom_condition) { continue; /* this will also restart bottom loop */ }
+    ...
+    }
+    ...
+  }
+  ....
+}

Task/Flow-control-structures/Lua/flow-control-structures.lua

@@ -0,0 +1,5 @@
+i = 0
+while true do
+    i = i + 1
+    if i > 10 then break end
+end

Task/Flow-control-structures/MUMPS/flow-control-structures-1.mumps

@@ -0,0 +1 @@
+GOTO LABEL^ROUTINE

Task/Flow-control-structures/MUMPS/flow-control-structures-2.mumps

@@ -0,0 +1 @@
+GOTO THERE

Task/Flow-control-structures/MUMPS/flow-control-structures-3.mumps

@@ -0,0 +1,2 @@
+ Read "Do you really wish to halt (Y/N)?",Q#1
+ IF Q="Y"!Q="y" HALT

Task/Flow-control-structures/MUMPS/flow-control-structures-4.mumps

@@ -0,0 +1 @@
+JOB LABEL^ROUTINE

Task/Flow-control-structures/MUMPS/flow-control-structures-5.mumps

@@ -0,0 +1 @@
+JOB THERE

Task/Flow-control-structures/MUMPS/flow-control-structures-6.mumps

@@ -0,0 +1 @@
+ JOB LABEL^ROUTINE

Task/Flow-control-structures/MUMPS/flow-control-structures-7.mumps

@@ -0,0 +1,2 @@
+FOR I=1:1:1 QUIT:NoLoop  DO YesLoop
+QUIT Returnvalue

Task/Flow-control-structures/MUMPS/flow-control-structures-8.mumps

@@ -0,0 +1,4 @@
+ SET A="SET %=$INCREMENT(I)"
+ SET I=0
+ XECUTE A
+ WRITE I

Task/Flow-control-structures/Maxima/flow-control-structures.maxima

@@ -0,0 +1,8 @@
+/* goto */
+block(..., label, ..., go(label), ...);
+
+/* throw, which is like trapping errors, and can do non-local jumps to return a value */
+catch(..., throw(value), ...);
+
+/* error trapping */
+errcatch(..., error("Bad luck!"), ...);

Task/Flow-control-structures/PHP/flow-control-structures.php

@@ -0,0 +1,7 @@
+<?php
+goto a;
+echo 'Foo';
+
+a:
+echo 'Bar';
+?>

Task/Flow-control-structures/Perl/flow-control-structures.pl

@@ -0,0 +1,3 @@
+FORK:
+# some code
+goto FORK;

Task/Flow-control-structures/Python/flow-control-structures-1.py

@@ -0,0 +1,10 @@
+# Search for an odd factor of a using brute force:
+for i in range(n):
+    if (n%2) == 0:
+        continue
+    if (n%i) == 0:
+        result = i
+        break
+else:
+    result = None
+    print "No odd factors found"

Task/Flow-control-structures/Python/flow-control-structures-10.py

@@ -0,0 +1,13 @@
+# Let's call our custom error "StupidError"; it inherits from the Exception class
+
+class StupidError(Exception): pass
+
+# Try it out.
+try:
+    raise StupidError("Segfault") # here, we manually 'raise' the error within the try block
+except StupidError, details: # 'details' is the StupidError object we create in the try block.
+    print 'Something stupid occurred:', details # so we access the value we had stored for it...
+
+
+# Output :
+# Something stupid occurred: Segfault

Task/Flow-control-structures/Python/flow-control-structures-11.py

@@ -0,0 +1,20 @@
+    i = 101
+    for i in range(4): # loop 4 times
+        print "I will always be seen."
+        if i % 2 == 0:
+            continue # continue goes back to the loop beginning for a new iteration.
+        print "I'll only be seen every other time."
+    else:
+        print "Loop done"
+
+    # Output:
+    # I will always be seen.
+    # I will always be seen.
+    # I'll only be seen every other time.
+    # I will always be seen.
+    # I will always be seen.
+    # I'll only be seen every other time.
+    # Loop done
+
+if(__name__ == "__main__"):
+    main()

Task/Flow-control-structures/Python/flow-control-structures-12.py

@@ -0,0 +1,9 @@
+class Quitting(Exception): pass
+max = 10
+with open("some_file") as myfile:
+    exit_counter = 0
+    for line in myfile:
+        exit_counter += 1
+        if exit_counter > max:
+            raise Quitting
+        print line,

Task/Flow-control-structures/Python/flow-control-structures-2.py

@@ -0,0 +1 @@
+class MyException(Exception): pass

Task/Flow-control-structures/Python/flow-control-structures-3.py

@@ -0,0 +1,3 @@
+class MyVirtual(object):
+    def __init__(self):
+        raise NotImplementedError

Task/Flow-control-structures/Python/flow-control-structures-4.py

@@ -0,0 +1,6 @@
+try:
+    temp = 0/0
+# 'except' catches any errors that may have been raised between the code of 'try' and 'except'
+except:   # Note: catch all handler ... NOT RECOMMENDED
+    print "An error occurred."
+# Output : "An error occurred"

Task/Flow-control-structures/Python/flow-control-structures-5.py

@@ -0,0 +1,6 @@
+try:
+    temp = 0/0
+# here, 'except' catches a specific type of error raised within the try block.
+except ZeroDivisionError:
+    print "You've divided by zero!"
+# Output : "You've divided by zero!"

Task/Flow-control-structures/Python/flow-control-structures-6.py

@@ -0,0 +1,11 @@
+try:
+    temp = 0/0
+except:
+    print "An error occurred."
+# here, 'finally' executes when the try - except block ends, regardless of whether an error was raised or not
+# useful in areas such as closing opened file streams in the try block whether they were successfully opened or not
+finally:
+    print "End of 'try' block..."
+# Output :
+# An error occurred
+# End of 'try' block...

Task/Flow-control-structures/Python/flow-control-structures-7.py

@@ -0,0 +1,8 @@
+try:
+    try:
+        pass
+    except (MyException1, MyOtherException):
+        pass
+    except SomeOtherException:
+finally:
+    do_some_cleanup() # run in any case, whether any exceptions were thrown or not

Task/Flow-control-structures/Python/flow-control-structures-8.py

@@ -0,0 +1,9 @@
+try:
+    temp = 1/1 # not a division by zero error
+except ZeroDivisionError: # so... it is not caught
+    print "You've divided by zero."
+# here, 'else' executes when no exceptions are caught...
+else:
+    print "No apparent error occurred."
+# Output :
+# No apparent error occurred.

Task/Flow-control-structures/Python/flow-control-structures-9.py

@@ -0,0 +1,20 @@
+i = 0
+while 1: # infinite loop
+    try:
+       temp2 = 0/i # will raise a ZeroDivisionError first.
+       temp = math.sqrt(i)
+
+       break # 'break' will break out of the while loop
+    except ValueError: #
+        print "Imaginary Number! Breaking out of loop"
+        break # 'break' out of while loop
+    except ZeroDivisionError:
+        print "You've divided by zero. Decrementing i and continuing..."
+        i-=1 # we decrement i.
+        # we 'continue', everything within the try - except block will be executed again,
+        # this time however, ZeroDivisionError would not be raised again.
+        continue # Note that removing it, replacing it with 'pass' would perform the equivalent
+                 # see below for a better example
+# Output :
+# You've divided by zero. Decrementing i and continuing...
+# Imaginary Number! Breaking out of loop

Task/Flow-control-structures/REXX/flow-control-structures-1.rexx

@@ -0,0 +1,3 @@
+exit
+
+exit  expression

Task/Flow-control-structures/REXX/flow-control-structures-2.rexx

@@ -0,0 +1,3 @@
+return
+
+return  expression

Task/Flow-control-structures/REXX/flow-control-structures-3.rexx

@@ -0,0 +1,39 @@
+signal on error
+signal on failure
+signal on halt
+signal on lostdigits
+signal on notready
+signal on novalue
+signal on syntax
+
+signal off error
+signal off failure
+signal off halt
+signal off lostdigits
+signal off notready
+signal off novalue
+signal off syntax
+ ∙
+ ∙
+ ∙
+signal on novalue
+ ∙
+ ∙
+x=oopsay+1
+ ∙
+ ∙
+ ∙
+novalue: say
+say '*** error! ***'
+say
+say 'undefined REXX variable' condition("D")
+say
+say 'in line' sigl
+say
+say 'REXX source statement is:'
+say sourceline(sigl)
+say
+exit 13
+ ∙
+ ∙
+ ∙

Task/Flow-control-structures/REXX/flow-control-structures-4.rexx

@@ -0,0 +1,22 @@
+  do j=1  to 10
+  say 'j=' j
+  if j>5  then leave
+  say 'negative j=' -j
+  end
+say 'end of the DO loop for j.'
+ ∙
+ ∙
+ ∙
+ouch=60
+sum=0
+
+  do k=0  to 100  by 3
+  say 'k=' k
+
+     do m=1  to k
+     if m=ouch  then leave k
+     sum=sum+m
+     end
+
+  end
+say 'sum=' sum

Task/Flow-control-structures/REXX/flow-control-structures-5.rexx

@@ -0,0 +1,24 @@
+sum=0
+
+  do j=1  to 1000
+  if j//3==0 | j//7==0  then iterate
+  sum=sum+j
+  end
+
+           /*shows sum of 1k numbers except those divisible by 3 or 7.*/
+say 'sum='sum
+ ∙
+ ∙
+ ∙
+numeric digits 5000
+prod=0
+
+  do k=1  to 2000
+
+     do m=1  to k
+     if m>99  then iterate k
+     prod=prod*m
+     end
+
+  end
+say 'prod=' prod

Task/Flow-control-structures/REXX/flow-control-structures-6.rexx

@@ -0,0 +1,18 @@
+numeric digits 1000               /*prepare for some gihugeic numbers.*/
+ ∙
+ ∙
+ ∙
+n=4
+call factorial n
+say n'!=' result
+exit
+
+
+factorial: parse arg x
+!=1
+
+  do j=2  to x
+  !=!*j
+  end
+
+return !

Task/Flow-control-structures/REXX/flow-control-structures-7.rexx

@@ -0,0 +1,25 @@
+ ∙
+ ∙
+ ∙
+prod=1
+a=7               /*or somesuch.*/
+b=3               /*  likewise. */
+
+op='**'           /*or whatever.*/
+ ∙
+ ∙
+ ∙
+  select
+  when op=='+'         then  r=a+b           /*add.                   */
+  when op=='-'         then  r=a-b           /*subtract.              */
+  when op=='*'         then do; r=a*b; prod=prod*r; end    /*multiply.*/
+  when op=='*'         then  r=a*b           /*multiply.              */
+  when op=='/'  & b\=0 then  r=a/b           /*divide.                */
+  when op=='%'  & b\=0 then  r=a/b           /*interger divide.       */
+  when op=='//' & b\=0 then  r=a/b           /*modulus (remainder).   */
+  when op=='||'        then  r=a||b          /*concatenation.         */
+  when op=='caw'       then  r=xyz(a,b)      /*call the XYZ subroutine*/
+  otherwise                  r='[n/a]'       /*signify not applicable.*/
+  end
+
+say 'result for' a op b "=" r

Task/Flow-control-structures/Ruby/flow-control-structures-1.rb

@@ -0,0 +1,13 @@
+begin
+  # some code that may raise an exception
+rescue ExceptionClassA => a
+  # handle code
+rescue ExceptionClassB, ExceptionClassC => b_or_c
+  # handle ...
+rescue
+  # handle all other exceptions
+else
+  # when no exception occurred, execute this code
+ensure
+  # execute this code always
+end

Task/Flow-control-structures/Ruby/flow-control-structures-2.rb

@@ -0,0 +1,3 @@
+values = ["1", "2.3", /pattern/]
+result = values.map {|v| Integer(v) rescue Float(v) rescue String(v)}
+# => [1, 2.3, "(?-mix:pattern)"]

Task/Flow-control-structures/Ruby/flow-control-structures-3.rb

@@ -0,0 +1,17 @@
+def some_method
+  # ...
+  if some_condition
+    throw :get_me_out_of_here
+  end
+  # ...
+end
+
+catch :get_me_out_of_here do
+  for ...
+    for ...
+      some_method
+    end
+  end
+end
+
+puts "continuing after catching the throw"

Task/Flow-control-structures/Tcl/flow-control-structures-1.tcl

@@ -0,0 +1 @@
+after 1000 {myroutine x}

Task/Flow-control-structures/Tcl/flow-control-structures-2.tcl

@@ -0,0 +1 @@
+after cancel myroutine

Task/Flow-control-structures/Tcl/flow-control-structures-3.tcl

@@ -0,0 +1,8 @@
+package require Tk
+proc update {} {
+    .clockface configure -text [clock format [clock seconds]]
+    after 1000 update ; # call yourself in a second
+}
+# now just create the 'clockface' and call ;update' once:
+pack [label .clockface]
+update

Task/Flow-control-structures/Tcl/flow-control-structures-4.tcl

@@ -0,0 +1,5 @@
+if {[catch { ''... code that might give error ...'' } result]} {
+    puts "Error was $result"
+} else {
+    ''... process $result ...''
+}

Task/Flow-control-structures/Tcl/flow-control-structures-5.tcl

@@ -0,0 +1,10 @@
+try {
+    # Just a silly example...
+    set f [open $filename]
+    expr 1/0
+    string length [read $f]
+} trap {ARITH DIVZERO} {} {
+    puts "divided by zero"
+} finally {
+    close $f
+}

Task/Flow-control-structures/Tcl/flow-control-structures-6.tcl

@@ -0,0 +1,8 @@
+proc forfilelines {linevar filename code} {
+    upvar $linevar line ; # connect local variable line to caller's variable
+    set filechan [open $filename]
+    while {[gets $filechan line] != -1} {
+      uplevel 1 $code   ; # Run supplied code in caller's scope
+    }
+    close $filechan
+}

Task/Flow-control-structures/Tcl/flow-control-structures-7.tcl

@@ -0,0 +1,3 @@
+forfilelines myline mydata.txt {
+    puts [string length $myline]
+}