strchr("fooeyfooeyfoo", 'f') = "fooeyfooeyfoo"

strrchr("fooeyfooeyfoo", 'f') = "foo"

strchr("fooeyfooeyfoo", 'y') = "yfooeyfoo"

strrchr("fooeyfooeyfoo", 'y') = "yfoo"

strrchr("yfooeyfoo", 'y') = "yfoo"

strchr("fooeyfooeyfoo", '') = ""

strrchr("fooeyfooeyfoo", '') = ""