Test MDX File V8

C++ Flow Lab

Flow Lab…

C++ Control Flow Lab

See how switch, break, and continue redirect program flow.

derekmolloy.ie

Switch (no break)

fall-through

Switch (with break)

normal exit

For + break/continue

skip & exit

Input value

x = 1x = 5x = 7

matches case 5

▶int x = 5;
▶switch (x) {
▶    case 1: cout << "test1";
▶    case 5: cout << "test5";
▶    default: cout << "none";
▶}

StartStepReset

Speed

slownormalfast

case matchcase bodybreak

Trace

Press Start or Step to begin…

Output

(nothing printed yet)

Without break, execution falls through from one matched case into every case below it — including default. Try x = 1 to see it cascade through every branch. This is occasionally useful, but almost always a bug.

C++ Loop Lab

Loop Lab…

C++ Loop Lab

Pick a loop type and watch the program counter walk it — see exactly where each loop checks, steps, and jumps back.

derekmolloy.ie

For Loop

init; cond; step

While Loop

cond at top

Do While

cond at bottom

Range-based For

C++11 for-each

▶int arr[] = {10, 20, 30, 40, 50};
▶int n = 5;
▶ 
▶for (int i = 0; i < n; i++) {
▶    cout << arr[i] << " ";
▶}

StartStepReset

Speed

slownormalfast

initconditionincrementbody

Trace

Press Start or Step to begin…

Output

(nothing printed yet)

All four loops produce the same output for this array, but their structure differs. for packs init, condition, and increment into one header. while separates them — init before the loop, increment inside the body. do-while tests the condition after the body, so the body always runs at least once — even if the condition starts false. range-based for (C++11) hides the counter, condition, and increment entirely — the compiler generates them so you can just say "for each element, do this".