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# `for`

`for` loops are the most complex loops in PHP. They behave like their C counterparts. The syntax of a `for` loop is:

    for (expr1; expr2; expr3) statement

The first expression (`expr1`) is evaluated (executed) once unconditionally at the beginning of the loop.

In the beginning of each iteration, `expr2` is evaluated. If it evaluates to `TRUE`, the loop continues and the nested statement(s) are executed. If it evaluates to `FALSE`, the execution of the loop ends.

At the end of each iteration, `expr3` is evaluated (executed).

Each of the expressions can be empty. `expr2` being empty means the loop should be run indefinitely (PHP implicitly considers it as `TRUE`, like C). This may not be as useless as you might think, since often you'd want to end the loop using a conditional `break` statement instead of using the `for` truth expression.

Consider the following examples. All of them display numbers from 1 to 10:

     /* example 1 */

     for ($i = 1; $i <= 10; $i++) {
         print $i;
     }

     /* example 2 */

     for ($i = 1;;$i++) {
         if ($i > 10) {
             break;
         }
         print $i;
     }

     /* example 3 */

     $i = 1;
     for (;;) {
         if ($i > 10) {
             break;
         }
         print $i;
         $i++;
     }

     /* example 4 */

     for ($i = 1; $i <= 10; print $i, $i++) ;

Of course, the first example appears to be the nicest one (or perhaps the fourth), but you may find that being able to use empty expressions in `for` loops comes in handy in many occasions.

PHP also supports the alternate "colon syntax" for `for` loops.

     for (expr1; expr2; expr3): statement; ...; endfor;

Other languages have a foreach statement to traverse an array or hash. PHP uses the while statement and the list() and each() functions for this. See the documentation for these functions for an example.

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