Questions tagged [control-flow]

Control flow (or flow of control) refers to the order in which statements are evaluated or executed.

There are many methods to control the flow of execution in a program:

Unconditional jumps can use labels:

foo:
printf ("Hello, world.\n");
goto foo;

... or line numbers:

10 PRINT "something"
20 GOTO 10

Conditional branching can use if-else constructs:

if ($x > 3) {
    print "$x is many.";
} else {
    print "$x is few.";
}

... or switch statements:

case n of
    1 : writeln('one');
    2 : writeln('two');
    3 : writeln('three');
end;

Loops of various kinds exist, including for loops:

for (var i = 0; i < 9; i++) {
    window.alert(i);
}

... foreach loops:

foreach (int x in myArray)
{
    Console.WriteLine(x);
}

... and while loops:

while read z
do
    echo "Hello, ${z}."
done

Loops can also be terminated early, or made to bypass some of the loop body, with break and continue statements respectively:

for club in ("groucho", "fight", "fight", "kitkat", "drones"):
    if club == "fight":
        continue
    if club == "kitkat":
        break
    print(club)

Functions temporarily divert execution to named sections of code, before returning:

hello = (name) -> "Hello, #{ name }."
console.log hello "world"

Exceptions are used to divert control flow in exceptional circumstances:

try {
    x = 1 / 0;
    System.out.println("Hello, world."); // is not reached
} catch (ArithmeticException e) {
    System.out.println("Goodbye, world.");
}