std::wcstok

 

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Technical Specifications

 

Strings library

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Null-terminated wide strings

Functions
Character manipulation
iswalnum iswalpha iswlower iswupper iswdigit iswxdigit iswblank (C++11) wctype iswctype	iswcntrl iswgraph iswspace iswprint iswpunct towlower towupper wctrans towctrans
Conversions to numeric formats
wcstolwcstoll wcstoulwcstoull	wcstofwcstodwcstold wcstoimaxwcstouimax (C++11)(C++11)
String manipulation
wcslen wcscpy wcsncpy wcscat wcsncat wcscmp wcscoll wcsncmp	wcsxfrm wcschr wcsrchr wcspbrk wcsspn wcscspn wcsstr wcstok
Array manipulation
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wmemchr
wmemset

 

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