Repetition

for (initializationExpression; loopCondition; stepExpression)
{
  // statements ...
}

Note that after evaluate initializationExpression, loopCondition is tested. If it fails then statements will not be executed.

while (symbol *ptr = search(name)) {
  // ptr visible only here
}
if (symbol *ptr = search(name)) {
  // ptr visible only here
}

In C++ and C99, scope of the variables declared (and normally initialized together, usually are looping counters) inside initializationExpression are within the for loop body. Similarly, object defined within the while and if condition is visible only within the associated statement or statement block.

Unlike the other loop statements, the condition of the do while loop does not support an object definition because the condition is not evaluated until after the statement or statement block is initially executed.

do {
  // statements ...
} while (int i = GetInt()); // error: declaration cannot within do while condition

do
{
  int i;
  // statements ...
} while (i = GetInt()); // logical error: i initialized again and again

int i;
do
{
  // statements ...
} while (i = GetInt()); // ok

Index