6 Statements [stmt.stmt]

6.5 Iteration statements [stmt.iter]

6.5.3 The for statement [stmt.for]

The for statement

for ( for-init-statement conditionopt ; expressionopt ) statement

is equivalent to

	while ( condition ) {
		expression ;

except that names declared in the for-init-statement are in the same declarative-region as those declared in the condition, and except that a continue in statement (not enclosed in another iteration statement) will execute expression before re-evaluating condition. [ Note: Thus the first statement specifies initialization for the loop; the condition ([stmt.select]) specifies a test, made before each iteration, such that the loop is exited when the condition becomes false; the expression often specifies incrementing that is done after each iteration.  — end note ]

Either or both of the condition and the expression can be omitted. A missing condition makes the implied while Clause equivalent to while(true).

If the for-init-statement is a declaration, the scope of the name(s) declared extends to the end of the for-statement. [ Example:

int i = 42;
int a[10];

for (int i = 0; i < 10; i++)
  a[i] = i;

int j = i;          // j = 42

 — end example ]