Question

I am new to PHP and regular expression. I was going thorugh some online examples and came with this example:

<?php
echo preg_replace_callback('~-([a-z])~', function ($match) {
    return strtoupper($match[1]);
}, 'hello-world');
// outputs helloWorld
?>

in php.net but to my surprise it does not work and keep getting error:

PHP Parse error:  parse error, unexpected T_FUNCTION

Why get error ?

Answer 1

You are using PHP’s Anonymous functions: functions that have no name.

When I run your program I get no error. May be you are trying it on a PHP < 5.3.

Anonymous functions are available since PHP 5.3.0.

If PHP version is creating the problem you can re-write the program to not use Anonymous functions as:

<?php

// a callback function called in place of anonymous function.
echo preg_replace_callback('~-([a-z])~','fun', 'hello-world');

// the call back function.
function fun($match) {
    return strtoupper($match[1]);
}

?>