PHP Regex allow only a-z A-Z 1-9 and replace spaces with underscore

Question

So i need preg_replace() to

remove all characters but a-z A-Z 1-9
replace spaces with single underscore \s+
if there's multiple underscores in string it need to be replaced with single one [_]+

Code

$str = "Hz!!    zÒ142______23 4";
$str = preg_replace('/[^a-zA-Z0-9][_]+\s+/', '_', $str);
echo $str; //Outputs: Hz_z142_23_4

Edit i'd like to do it with single preg_replace

@bansi That will also replace `Ò` with `_`, which OP doesn't want. — Rohit Jain, Dec 19 '15 at 05:37
Possible duplicate of [How to remove non-alphanumeric characters?](http://stackoverflow.com/questions/659025/how-to-remove-non-alphanumeric-characters) — But those new buttons though.., Dec 19 '15 at 05:41

Rohit Jain · Answer 1 · 2015-12-19T05:38:03.237

4

You can do it in two replacements:

$str = preg_replace('/[^\w\s]+/', '', $str);
$str = preg_replace('/[^a-zA-Z0-9]+/', '_', $str);

Or, as in comments, you can combine them into one:

preg_replace(array('/[^\w\s]+/', '/[^a-zA-Z0-9]+/'), array('', '_'), $str);

edited Dec 19 '15 at 05:38

answered Dec 19 '15 at 05:28

Rohit Jain

`preg_replace(array('/[^\w\s]+/','/[^a-zA-Z0-9]+/'), array('','_'), $str);` just combine it all to become one – roullie Dec 19 '15 at 05:33
How would i go about adding say one more symbol to allowd say exclamation mark "!" – Roman Toasov Dec 20 '15 at 01:18
Roman Toasov put it after the \s inside the brackets and 9 inside the brackets. – JSG Oct 02 '20 at 05:31

1 Answers1