C++ In a Nutshell

Control Statements

Control statements change execution from its normal sequence. When execution leaves a scope, all automatic objects that were created in that scope are destroyed. (see Chapter 2 for a discussion of automatic and other object lifetimes)

C++ supports the following control statements:

break;

A break statement can be used only in the body of a loop or switch statement. It terminates the loop or switch statement and transfers execution to the statement immediately following the loop or switch.

In a nested loop or switch, the break applies only to the innermost statement. To break out of multiple loops and switches, you must use a goto statement or redesign the block to avoid nested loops and switches (by factoring the inner statement into a separate function, for example). Example 4-7 shows a simple use of break.

Example 4-7. Using break to exit a loop

// One way to implement the find_if standard algorithm.
template<typename InIter, typename Predicate>
InIter find_if(InIter first, InIter last, Predicate pred)
{
  for ( ; first != last; ++first)
    if (pred(*first))      break;

  return first;
}

continue;

A continue statement can be used only in the body of a loop. It causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating (if the condition is true). In a for loop, the iterate-expr is evaluated before testing the condition. Example 4-8 shows how continue is used in a loop.

Example 4-8. Using continue in a loop

#include <cmath> #include ...