PHP CookBook

Recipe 6.7 Returning Values by Reference

6.7.1 Problem

You want to return a value by reference, not by value. This allows you to avoid making a duplicate copy of a variable.

6.7.2 Solution

The syntax for returning a variable by reference is similar to passing it by reference. However, instead of placing an & before the parameter, place it before the name of the function:

function &wrap_html_tag($string, $tag = 'b') {
    return "<$tag>$string</$tag>";
}

Also, you must use the =& assignment operator instead of plain = when invoking the function:

$html =& wrap_html_tag($string);

6.7.3 Discussion

Unlike passing values into functions, in which an argument is either passed by value or by reference, you can optionally choose not to assign a reference and just take the returned value. Just use = instead of =&, and PHP assigns the value instead of the reference.

6.7.4 See Also

Recipe 6.4 on passing values by reference.