pub fn strrchr(cs: *const c_char, c: c_int) -> *mut c_char;
pub fn strspn(cs: *const c_char, ct: *const c_char) -> size_t;
pub fn strcspn(cs: *const c_char, ct: *const c_char) -> size_t;
+ pub fn strdup(cs: *const c_char) -> *mut c_char;
pub fn strpbrk(cs: *const c_char, ct: *const c_char) -> *mut c_char;
pub fn strstr(cs: *const c_char, ct: *const c_char) -> *mut c_char;
pub fn strlen(cs: *const c_char) -> size_t;