Compares two strings, ignoring differences in case.
#include <string.h>
int strcasecmp (
const char *s1,
const char *s2);
(IN) Points to the first string to compare.
(IN) Points to the second string to compare.
Returns 0 if the two strings match. Otherwise, it returns an integer less than or greater than 0, depending on whether s1 is lexicographically less than or greater than s2.
The strcasecmp function is identical to strcmp, except that the characters of each string are converted to lowercase before comparison.
Each character is treated as if it is of type unsigned char, and NULL pointers are treated as pointers to empty strings.