Regexp : catching all letters and numbers before a specific string

I would like to catch, in order to replace, all letters and numbers placed before a specific string in one preg_replace.

Example : a_dress.mail-123@aol.fr Result : a_aaaaa.aaaa-aaa@aol.fr

I tried (([a-z]*[^\.\-\_]*)|\d*[^\.\-\_]*)(?=(@(?:[\w-]+\.)+[\w-]{2,4})) but it only gets the last matching

You can use

preg_replace('/[a-zA-Z0-9](?=[^\s@]*@)/', 'a', $text)
preg_replace('/[^\W_](?=[^\s@]*@)/', 'a', $text)

See the regex demo.

Details

• [^\W_] / [a-zA-Z0-9] - a letter or digit
• (?=[^\s@]*@) - immediately to the right, there must be zero or more chars other than whitespaces and @ and then a @ char.