The wcscat() and wscat() functions append a copy of the wide-character string pointed to by ws2 (including the terminating null wide-character code) to the end of the wide-character string pointed to by ws1. The initial wide-character code of ws2 overwrites the null wide-character code at the end of ws1. If copying takes place between objects that overlap, the behavior is undefined. Both functions return s1; no return value is reserved to indicate an error.

The wcsncat() and wsncat() functions append not more than n wide-character codes (a null wide-character code and wide-character codes that follow it are not appended) from the array pointed to by ws2 to the end of the wide-character string pointed to by ws1. The initial wide-character code of ws2 overwrites the null wide-character code at the end of ws1. A terminating null wide-character code is always appended to the result. Both functions return ws1; no return value is reserved to indicate an error.

The wcscmp() and wscmp() functions compare the wide-character string pointed to by ws1 to the wide-character string pointed to by ws2. The sign of a non-zero return value is determined by the sign of the difference between the values of the first pair of wide-character codes that differ in the objects being compared. Upon completion, both functions return an integer greater than, equal to, or less than zero, if the wide-character string pointed to by ws1 is greater than, equal to, or less than the wide-character string pointed to by ws2.

The wcsncmp() and wsncmp() functions compare not more than n wide-character codes (wide-character codes that follow a null wide character code are not compared) from the array pointed to by ws1 to the array pointed to by ws2. The sign of a non-zero return value is determined by the sign of the difference between the values of the first pair of wide-character codes that differ in the objects being compared. Upon successful completion, both functions return an integer greater than, equal to, or less than zero, if the possibly null-terminated array pointed to by ws1 is greater than, equal to, or less than the possibly null-terminated array pointed to by ws2.

The wcscpy() and wscpy() functions copy the wide-character string pointed to by ws2 (including the terminating null wide-character code) into the array pointed to by ws1. If copying takes place between objects that overlap, the behavior is undefined. Both functions return ws1; no return value is reserved to indicate an error.

The wcsncpy() and wsncpy() functions copy not more than n wide-character codes (wide-character codes that follow a null wide character code are not copied) from the array pointed to by ws2 to the array pointed to by ws1. If copying takes place between objects that overlap, the behavior is undefined. If the array pointed to by ws2 is a wide-character string that is shorter than n wide-character codes, null wide-character codes are appended to the copy in the array pointed to by ws1, until a total n wide-character codes are written. Both functions return ws1; no return value is reserved to indicate an error.

The wcslen() and wslen() functions compute the number of wide-character codes in the wide-character string to which ws points, not including the terminating null wide-character code. Both functions return ws; no return value is reserved to indicate an error.

The wcschr() and wschr() functions locate the first occurrence of wc in the wide-character string pointed to by ws. The value of wc must be a character representable as a type wchar_t and must be a wide-character code corresponding to a valid character in the current locale. The terminating null wide-character code is considered to be part of the wide-character string. Upon completion, both functions return a pointer to the wide-character code, or a null pointer if the wide-character code is not found.

The wcsrchr() and wsrchr() functions locate the last occurrence of wc in the wide-character string pointed to by ws. The value of wc must be a character representable as a type wchar_t and must be a wide-character code corresponding to a valid character in the current locale. The terminating null wide-character code is considered to be part of the wide-character string. Upon successful completion, both functions return a pointer to the wide-character code, or a null pointer if wc does not occur in the wide-character string.

The windex() and wrindex() functions behave the same as wschr() and wsrchr(), respectively.

The wcspbrk() and wspbrk() functions locate the first occurrence in the wide character string pointed to by ws1 of any wide-character code from the wide-character string pointed to by ws2. Upon successful completion, the function returns a pointer to the wide-character code, or a null pointer if no wide-character code from ws2 occurs in ws1.

The wcswcs() function locates the first occurrence in the wide-character string pointed to by ws1 of the sequence of wide-character codes (excluding the terminating null wide-character code) in the wide-character string pointed to by ws2. Upon successful completion, the function returns a pointer to the located wide-character string, or a null pointer if the wide-character string is not found. If ws2 points to a wide-character string with zero length, the function returns ws1.

The wcsspn() and wsspn() functions compute the length of the maximum initial segment of the wide-character string pointed to by ws1 which consists entirely of wide-character codes from the wide-character string pointed to by ws2. Both functions return the length ws1; no return value is reserved to indicate an error.

The wcscspn() and wscspn() functions compute the length of the maximum initial segment of the wide-character string pointed to by ws1 which consists entirely of wide-character codes not from the wide-character string pointed to by ws2. Both functions return the length of the initial substring of ws1; no return value is reserved to indicate an error.

A sequence of calls to the wcstok() and wstok() functions break the wide-character string pointed to by ws1 into a sequence of tokens, each of which is delimited by a wide-character code from the wide-character string pointed to by ws2.

The third argument points to a caller-provided wchar_t pointer into which the wcstok() function stores information necessary for it to continue scanning the same wide-character string. This argument is not available with the XPG4 and SUS versions of wcstok(), nor is it available with the wstok() function. See standards(5).

The first call in the sequence has ws1 as its first argument, and is followed by calls with a null pointer as their first argument. The separator string pointed to by ws2 may be different from call to call.

The first call in the sequence searches the wide-character string pointed to by ws1 for the first wide-character code that is not contained in the current separator string pointed to by ws2. If no such wide-character code is found, then there are no tokens in the wide-character string pointed to by ws1, and wcstok() and wstok() return a null pointer. If such a wide-character code is found, it is the start of the first token.

The wcstok() and wstok() functions then search from that point for a wide-character code that is contained in the current separator string. If no such wide-character code is found, the current token extends to the end of the wide-character string pointed to by ws1, and subsequent searches for a token will return a null pointer. If such a wide-character code is found, it is overwritten by a null wide character, which terminates the current token. The wcstok() and wstok() functions save a pointer to the following wide-character code, from which the next search for a token will start.

Each subsequent call, with a null pointer as the value of the first argument, starts searching from the saved pointer and behaves as described above.

Upon successful completion, both functions return a pointer to the first wide-character code of a token. Otherwise, if there is no token, a null pointer is returned.