# std::wcstok

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< cpp‎ | string‎ | wide

Defined in header `<cwchar>` |  |
wchar_t* wcstok( wchar_t* str, const wchar_t* delim, wchar_t ** ptr); |  |

Finds the next token in a null-terminated wide string pointed to by `str`. The separator characters are identified by null-terminated wide string pointed to by `delim`.

This function is designed to be called multiples times to obtain successive tokens from the same string.

  - If str != NULL, the call is treated as the first call to `std::wcstok` for this particular wide string. The function searches for the first wide character which is not contained in `delim`.
    - If no such wide character was found, there are no tokens in `str` at all, and the function returns a null pointer.
    - If such wide character was found, it is the beginning of the token. The function then searches from that point on for the first wide character that is contained in `delim`.
      - If no such wide character was found, `str` has only one token, and future calls to `std::wcstok` will return a null pointer
      - If such wide character was found, it is replaced by the null wide character L'\0' and the parser state (typically a pointer to the following wide character) is stored in the user-provided location *ptr.
    - The function then returns the pointer to the beginning of the token
  - If str == NULL, the call is treated as a subsequent calls to `std::wcstok`: the function continues from where it left in previous invocation with the same *ptr. The behavior is the same as if the pointer to the wide character that follows the last detected token is passed as str.

### Parameters

str | - | pointer to the null-terminated wide string to tokenize
delim | - | pointer to the null-terminated wide string identifying delimiters
ptr | - | pointer to an object of type wchar_t*, which is used by wcstok to store its internal state

### Return value

Pointer to the beginning of the next token or null pointer if there are no more tokens.

### Note

This function is destructive: it writes the L'\0' characters in the elements of the string `str`. In particular, a wide string literal cannot be used as the first argument of `std::wcstok`.

Unlike std::strtok, this function does not update static storage: it stores the parser state in the user-provided location.

Unlike most other tokenizers, the delimiters in `std::wcstok` can be different for each subsequent token, and can even depend on the contents of the previous tokens.

### Example

Run this code

    #include <cwchar>
    #include <iostream>

    int main()
    {
        wchar_t input[100] = L"A bird came down the walk";
        wchar_t* buffer;
        wchar_t* token = std::wcstok(input, L" ", &buffer);
        while (token) {
            std::wcout << token << '\n';
            token = std::wcstok(nullptr, L" ", &buffer);
        }
    }

Output:

    A
    bird
    came
    down
    the
    walk

### See also

strtok | finds the next token in a byte string (function)
C documentation for wcstok

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