iteration-statement: while ( condition ) statement do statement while ( expression ) ; for ( init-statement condition ; expression ) statement for ( for-range-declaration : for-range-initializer ) statement
for-range-declaration: attribute-specifier-seq decl-specifier-seq declarator attribute-specifier-seq decl-specifier-seq ref-qualifier [ identifier-list ]
for-range-initializer: expr-or-braced-init-listSee [dcl.meaning] for the optional attribute-specifier-seq in a for-range-declaration.
void f() { for (int i = 0; i < 10; ++i) int i = 0; // error: redeclaration for (int i : { 1, 2, 3 }) int i = 1; // error: redeclaration }
while (T t = x) statement
label: { // start of condition scope T t = x; if (t) { statement goto label; } } // end of condition scopeThe variable created in a condition is destroyed and created with each iteration of the loop.
struct A {
int val;
A(int i) : val(i) { }
~A() { }
operator bool() { return val != 0; }
};
int i = 1;
while (A a = i) {
// ...
i = 0;
}
for ( init-statement condition ; expression ) statementis equivalent to
{ init-statement while ( condition ) { statement expression ; } }except that names declared in the 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.
int i = 42;
int a[10];
for (int i = 0; i < 10; i++)
a[i] = i;
int j = i; // j = 42
for ( for-range-declaration : for-range-initializer ) statementis equivalent to
{ auto &&__range = for-range-initializer ; auto __begin = begin-expr ; auto __end = end-expr ; for ( ; __begin != __end; ++__begin ) { for-range-declaration = *__begin; statement } }where