substr_compare -- Binary safe optionally case insensitive comparison of 2 strings from an offset, up to length characters
int substr_compare ( string main_str, string str, int offset [, int length [, bool case_insensitivity]] )
substr_compare() compares main_str from position offset with str up to length characters.
Returns < 0 if main_str from position offset is less than str, > 0 if it is greater than str, and 0 if they are equal. If length is equal or greater than length of main_str and length
is set, substr_compare() prints warning and returns FALSE.
If case_insensitivity is TRUE, comparison is case insensitive.