This function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.
pattern
A POSIX extended regular expression.
replacement
If pattern
contains parenthesized substrings,
replacement
may contain substrings of the form
\\digit, which will be
replaced by the text matching the digit'th parenthesized substring;
\\0 will produce the entire contents of string.
Up to nine substrings may be used. Parentheses may be nested, in which
case they are counted by the opening parenthesis.
string
The input string.
The modified string is returned. If no matches are found in
string
, then it will be returned unchanged.