C Programming/C Reference/nonstandard/strcasecmp

In programming language C, strcasecmp is a function declared in the strings.h header file (or sometimes in string.h) that compares two strings irrespective of the case of characters.

This function is in POSIX.1-2001.

Prototype
This function returns an integer i :

i > 0, if lowercase(f1) is greater than lowercase(f2)

i < 0, if lowercase(f1) is found less than string lowercase(f2) and

i = 0, if lowercase(f1) is equal to lowercase(f2).