B.3 Treating Strings as Arrays Causes Errors

PHP 5 complains louder than PHP 4 when you treat a string as an array.

Accessing a multidimensional array element causes a fatal error in PHP 5:

 $string = 'string'; print $string[0][0];  PHP Fatal error:  Cannot use string offset as an array  

You can still access an individual character in a string using array notation, but as of PHP 4, this is deprecated in favor of curly braces ( { } ):

 $string = 'string'; // valid, but deprecated for ($i = 0; $i < strlen($string); $i++) {     print $string[$i]; } // valid, and preferred for ($i = 0; $i < strlen($string); $i++) {     print $string{$i}; }  string   string  

Passing strings to array_merge( ) and other array functions generates a warning in PHP 5:

 $string = "string"; $array = array_merge($string, $string);  PHP Warning:  array_merge( ): Argument #1 is not an array   PHP Warning:  array_merge( ): Argument #2 is not an array  

This does not generate any messages in PHP 4.