PHP Functions Essential Reference

eregi_replace

string eregi_replace(string pattern, string replace, string subject) 

pattern	Regex pattern to match
replace	Replacement string
subject	String to search using the pattern

Performs a non-case-sensitive POSIX regular expression match and replaces the matches in the subject with the specified replacement.

Returns:

Modified string if the pattern matched; unmodified string if not

Description:

This function works like ereg_replace() except for ignoring the case when matching alphabetic characters.

See also:

ereg_replace() 
preg_replace() 

Example:

Keep quips up to date (non-case-sensitive version)

$string = "Best way to dispose of the Borg: Give them WINDOWS ME."; echo eregi_replace("(Windows[ ]*)(3.1|95|98|me|2000|nt)", '\1XP', ...