THINK++ — Engineering Visualized

Conditional Loop

The while Loop

Repeats a block as long as the condition is true. The condition is checked before each iteration, so the body may never execute.

SYNTAX

while (condition) {
    // body
    // must update condition!
}

Count digits in a number

int n = 12345, count = 0;
while (n > 0) {
    count++;
    n /= 10;
}
// count = 5

Read until EOF

int x;
while (cin >> x) {
    // process x
}

⚠ INFINITE LOOP DANGER

Always ensure the loop condition will eventually become false. Forgetting to update the variable causes an infinite loop.

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