c/string/byte/strlen

@1@ Returns the length of the given null-terminated byte string, that is, the number of characters in a character array whose first element is pointed to by up to and not including the first null character. @@The behavior is undefined if is not a pointer to a null-terminated byte string. @2@ Same as, except that the function returns zero if is a null pointer and returns  if the null character was not found in the first  bytes of. @@The behavior is undefined if both points to a character array which lacks the null character and the size of that character array < ; in other words, an erroneous value of  does not expose the impending buffer overflow.

Return value
@1@ The length of the null-terminated byte string. @2@ The length of the null-terminated byte string on success, zero if  is a null pointer,  if the null character was not found.