Replace an upper-case string with lower-case using preg_replace() and regex

Question

Is it possible to replace an upper-case with lower-case using preg_replace and regex?

For example:

The following string:

$x="HELLO LADIES!";

I want to convert it to:

 hello ladies!

using preg_replace():

 echo preg_replace("/([A-Z]+)/","$1",$x);

I don't think you can do that with `preg_replace` alone as there is no pattern. Why not using `strtolower` ? — Alexandre Leprêtre, Dec 22 '15 at 16:34
Possible duplicate of [How to transform a string to lowercase with preg\_replace](http://stackoverflow.com/questions/9939066/how-to-transform-a-string-to-lowercase-with-preg-replace) — u_mulder, Dec 22 '15 at 16:34
`$x="HELLO LADIES!"; $x=strtolower($x);` ;-) as a quick one-liner if you don't need the preg_ function. — Funk Forty Niner, Dec 22 '15 at 16:55
Possible duplicate of [How to convert array values to lowercase in PHP?](https://stackoverflow.com/questions/11008443/how-to-convert-array-values-to-lowercase-in-php) — , May 08 '18 at 15:16

score 43 · Accepted Answer · answered Dec 22 '15 at 16:41

43

I think this is what you are trying to accomplish:

$x="HELLO LADIES! This is a test";
echo preg_replace_callback('/\b([A-Z]+)\b/', function ($word) {
      return strtolower($word[1]);
      }, $x);

Output:

hello ladies! This is a test

If you just want the whole string to be lowercase though than just use strtolower on the whole thing.

answered Dec 22 '15 at 16:41

chris85

3

I did not know it would be so easy with strtolower() and preg_replace() together. Thanks chris. – Amit Verma Dec 22 '15 at 16:51
2

Fantastic solution. I've just spent ages trying to look up / find out how to capitalise a capture group in PHP's PCRE Regex. It never occurred to me that PHP might have its own native function for transforming capture groups using PHP, rather than regex syntax. – Rounin Jun 02 '21 at 12:56

1 Answers1