#include <fontconfig.h>
FcChar8 * FcStrStrIgnoreCase(const FcChar8 *s1, const FcChar8 *s2);
FcChar8 * FcStrStrIgnoreCase
Returns the location of s2 in s1, ignoring case. Returns NULL if s2 is not present in s1. This test is case-insensitive for all proper UTF-8 encoded strings.
Fontconfig version 2.8.0