8 Statements [stmt.stmt]

8.6 Iteration statements [stmt.iter]

8.6.1 General [stmt.iter.general]

Iteration statements specify looping.
[Note 1: 
An init-statement ends with a semicolon.
— end note]
The substatement in an iteration-statement implicitly defines a block scope which is entered and exited each time through the loop.
If the substatement in an iteration-statement is a single statement and not a compound-statement, it is as if it was rewritten to be a compound-statement containing the original statement.
[Example 1: 
while (--x >= 0) int i; can be equivalently rewritten as while (--x >= 0) { int i; }
Thus after the while statement, i is no longer in scope.
— end example]