The do statement executes until the condition becomes false. The syntax of the do statement is:

do statement while (expression);

The statement is executed repeatedly as long as the value of expression remains non-zero. The expression is evaluated after each iteration, so the loop will execute statement at least once.

Parentheses around expression are mandatory.

Note that do is the only control structure in C which explicitly ends with semicolon (;). Other control structures end with statement, which means that they implicitly include a semicolon or closing brace.

Here is an example of calculating scalar product of two vectors, using the do statement:

s = 0; i = 0;
do {
  s += a[i] * b[i];
  i++;
} while ( i < n );

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