PHP Functions Essential Reference

eregi

string eregi(string pattern, string subject, [array matches]) 

pattern	Regex pattern to match
subject	String to search using the pattern
matches	Array in which to store the search results

Performs a non-case-sensitive POSIX regular expression match against the specified string.

Returns:

FALSE if no match is found; otherwise, the length of the full match if the matches parameter is specified or 1 if it’s not specified

Description:

This function works like ereg() except that it ignores the case when matching alphabetic characters. See ereg() for a description of its parameters and usage.

Note:

eregi() handles case properly for ISO-8859-1 8-bit alphabetic characters such as Å and å.

See also:

ereg() 
preg_match() 
preg_match_all()