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<HTML
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>Returning values</TITLE
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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="KEYWORD.FUNCTION.RETURN"
>Returning values</A
></H1
><P
>      Values are returned by using the optional return statement. Any
      type may be returned, including lists and objects.
 
      <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function my_sqrt ($num) {
     return $num * $num;
 }
 echo my_sqrt (4);   // outputs '16'.
       </PRE
><P
></P
></DIV
>
      
     </P
><P
>      Multiple values may not be returned, but the same effect can be
      achieved by returning a list:
 
      <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function foo() {
    return array (0, 1, 2);
 }
 list ($zero, $one, $two) = foo();
       </PRE
><P
></P
></DIV
>
 
    </P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="KEYWORD.FUNCTION.ARGUMENTS"
>Arguments</A
></H2
><P
>      Information may be passed to functions via the argument list,
      which is a comma-delimited list of variables and/or constants.
 
     </P
><P
>      PHP supports passing arguments by value (the default), <A
HREF="keyword.function.return.html#KEYWORD.FUNCTION.ARGUMENTS.REFERENCE"
>passing by
      reference</A
>, and <A
HREF="keyword.function.return.html#KEYWORD.FUNCTION.ARGUMENTS.DEFAULT"
>default argument
      values</A
>. Variable-length argument lists are not supported,
      but a similar effect may be achieved by passing arrays.
 
      <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function takes_array($input) {
     echo "$input[0] + $input[1] = ", $input[0]+$input[1];
 }
       </PRE
><P
></P
></DIV
>
 
     </P
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="KEYWORD.FUNCTION.ARGUMENTS.REFERENCE"
>Passing by reference</A
></H3
><P
>       By default, function arguments are passed by value. If you wish
       to allow a function to modify its arguments, you may pass them
       by reference.
       
      </P
><P
>       If you wish a function's argument to always be passed by
       reference, you can prepend an ampersand (&amp;) to the argument
       name in the function definition:
 
       <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function foo( &amp;$bar ) {
     $bar .= 'and something extra.';
 }
 $str = 'This is a string, ';
 foo ($str);
 echo $str;    // outputs 'This is a string, and something extra.'
        </PRE
><P
></P
></DIV
>
 
      </P
><P
>       If you wish to pass a variable by reference to a function which
       does not do this by default, you may prepend an ampersand to the 
       argument name in the function call:
 
       <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function foo ($bar) {
     $bar .= ' and something extra.';
 }
 $str = 'This is a string, ';
 foo ($str);
 echo $str;    // outputs 'This is a string, '
 foo (&amp;$str);
 echo $str;    // outputs 'This is a string, and something extra.'
        </PRE
><P
></P
></DIV
>
 
     </P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="KEYWORD.FUNCTION.ARGUMENTS.DEFAULT"
>Default values</A
></H3
><P
>       A function may define C++-style default values for scalar
       arguments as follows:
 
       <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function makecoffee ($type = "cappucino") {
     echo "Making a cup of $type.\n";
 }
 echo makecoffee ();
 echo makecoffee ("espresso");
        </PRE
><P
></P
></DIV
>
 
      </P
><P
>       The output from the above snippet is:
 
       <PRE
CLASS="SCREEN"
> Making a cup of cappucino.
 Making a cup of espresso.
       </PRE
>
 
      </P
><P
>       The default value must be a constant expression, not (for
       example) a variable or class member.
 
      </P
><P
>       Note that when using default arguments, any defaults should be
       on the right side of any non-default arguments; otherwise,
       things will not work as expected. Consider the following code
       snippet:
 
       <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function makeyogurt ($type = "acidophilus", $flavour) {
     return "Making a bowl of $type $flavour.\n";
 }
 
 echo makeyogurt ("raspberry");   // won't work as expected
        </PRE
><P
></P
></DIV
>
 
      </P
><P
>       The output of the above example is:
 
       <PRE
CLASS="SCREEN"
> Warning: Missing argument 2 in call to makeyogurt() in 
 /usr/local/etc/httpd/htdocs/php3test/functest.html on line 41
 Making a bowl of raspberry .
       </PRE
>
 
      </P
><P
>       Now, compare the above with this:
 
       <DIV
CLASS="INFORMALEXAMPLE"
><P
></P
><PRE
CLASS="PROGRAMLISTING"
> function makeyogurt ($flavour, $type = "acidophilus") {
     return "Making a bowl of $type $flavour.\n";
 }
 
 echo makeyogurt ("raspberry");   // works as expected
        </PRE
><P
></P
></DIV
>
 
      </P
><P
>       The output of this example is:
 
       <PRE
CLASS="SCREEN"
> Making a bowl of acidophilus raspberry.
      </PRE
>
 
   </P
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