1strchr("fooeyfooeyfoo", 'f') = "fooeyfooeyfoo"
2strrchr("fooeyfooeyfoo", 'f') = "foo"
3strchr("fooeyfooeyfoo", 'y') = "yfooeyfoo"
4strrchr("fooeyfooeyfoo", 'y') = "yfoo"
5strrchr("yfooeyfoo", 'y') = "yfoo"
6
7