FUNCTION

在PHP3中，您也可以定義一些函數，定義的方式大概如下：

    function foo( $arg_1, $arg_2, ..., $arg_n ) {
    　echo "Example function.\n";
      return $retval;
     }
       

傳回值

如果在函數中要傳回值，可以使用 Return

範例1：傳回單一值

    function my_sqrt( $num ) {
     return $num * $num;
     }
     echo my_sqrt( 4 ); // outputs '16'.
          

範例2:傳回多重值

    function foo() {
     return array( 0, 1, 2 );
     }
    list( $zero, $one, $two ) = foo();
           

函數參數

在程式中，您也可以傳遞參數至函數中處理，參數傳遞又分為 Passing by reference 及 Passing by value，預設值為 Passing by value。

範例1:Passing by reference

    function foo( &$bar ) {
     $bar .= ' and something extra.';
     }
     $str = 'This is a string, ';
       foo2( $str );
       echo $str; // outputs 'This is a string, and something extra.'
          

範例2:Passing by value

    function foo( $bar ) {
     $bar .= ' and something extra.';
      }
     $str = 'This is a string, ';
      foo2( $str );
     echo $str; // outputs 'This is a string, '
      foo2( &$str );
     echo $str; // outputs 'This is a string, and something extra.'