PHP strip punctuation

Question

Let's say I have this:

$hello = "Hello, is StackOverflow a helpful website!? Yes!"; 

and I want to strip punctuation so it outputs as:

hello_is_stackoverflow_a_helpful_website_yes 

How can I do that?

Answer 1

# to keep letters & numbers $s = preg_replace('/[^a-z0-9]+/i', '_', $s); # or... $s = preg_replace('/[^a-z\d]+/i', '_', $s);  # to keep letters only $s = preg_replace('/[^a-z]+/i', '_', $s);   # to keep letters, numbers & underscore $s = preg_replace('/[^\w]+/', '_', $s);  # same as third example; suggested by @tchrist; ^\w = \W $s = preg_replace('/\W+/', '_', $s); 

for string

$s = "Hello, is StackOverflow a helpful website!? Yes!"; 

result (for all examples) is

Hello_is_StackOverflow_a_helpful_website_Yes_

Enjoy!