How to change PHP's eregi to preg_match [duplicate]

Answer 1

You will need to change three things

1. need to add pattern delimiters (can be any character, but most commonly a forward slash)
2. [[:alnum:]] will need to be replaced with the PCRE equivalent
3. The "i" in "eregi" means case-insensitive, which PCRE does with a flag, specifically the i flag.

Otherwise, the rest looks PCRE compatible (yes, that's kind of redundant =P)

"/^[a-z0-9][a-z0-9_.-]*@[a-z0-9.-]+\.[a-z]{2,4}$/i"