[FIXED] How do you make preg_replace captures uppercase (php)?

Issue

I have a string: 'Some_string_to_capitalize' which I would like to transform to 'Some_String_To_Capitalize'. I have tried:

$result = preg_replace( '/(_([a-z]{1}))/' , strtoupper('$1') , $subject  )

and

$result = preg_replace( '/(_([a-z]{1}))/' , "strtoupper($1)" , $subject  )

I looked at the php man page and here on SO but found nothing. Apologies if this is a dup!

This is the equivalent SO question for Javascript.

Solution

I think you want to use preg_replace_callback:

In PHP 5.3+

<?php
$subject = 'Some_string_to_capitalize';
$result = preg_replace_callback(
    '/(_([a-z]{1}))/',
    function ($matches) {
        return strtoupper($matches[0]);
    } ,
    $subject
);

For PHP below 5.3

function toUpper($matches) {
    return strtoupper($matches[0]);
}

$result = preg_replace_callback('/(_([a-z]{1}))/', 'toUpper', $subject);

Answered By - David Stockton

Answer Checked By - Gilberto Lyons (PHPFixing Admin)