Content-type: text/html Man page of wcstok

wcstok

Section: C Library Functions (3)
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NAME

wcstok, wcstok_r - Split wide-character strings into tokens  

LIBRARY

Standard C Library (libc.so, libc.a)  

SYNOPSIS

#include <wchar.h>

wchar_t *wcstok(
        wchar_t *ws1,
        const wchar_t *ws2);

wchar_t *wcstok(
        wchar_t *ws1,
        const wchar_t *ws2),
        wchar_t **savept);

The wcstok() function that conforms to the XPG4 standard has two parameters rather than three; the savept parameter, which is required for threadsafe operation, is included only in the wcstok() function that conforms to the latest ISO C standard. The following threadsafe interface is supported only for backward compatibility with Tru64 UNIX versions prior to Version 4.0:

wchar_t *wcstok_r(
        wchar_t *ws1,
        const wchar_t *ws2),
        wchar_t **savept);  

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

wcstok(): ISO C, XPG4

Refer to the standards(5) reference page for more information about industry standards and associated tags.  

PARAMETERS

Contains a pointer to the wide-character string to be searched. Contains a pointer to the string of wide-character token delimiters. [ISO C]  Identifies the location of the wide character where the search for tokens should be started in the next call. The savept parameter contains a pointer to a variable that contains a pointer to the wide character where scanning begins.  

DESCRIPTION

The wcstok() function splits the wide-character string pointed to by the ws1 parameter into a sequence of tokens, each of which is delimited by a wide character from the wide-character string pointed to by the ws2 parameter.

Usually, the wcstok() function is called repeatedly to extract the tokens in a wide-character string. On the first call to the wcstok() function, the application sets the ws1 parameter to point to the input wide-character string. The function returns a pointer to the first token.

The application program calls the function again with the ws1 parameter set to the null pointer. This call returns a pointer to the next token in the string. The application program repeats the call to wcstok() with the ws1 parameter set to the null pointer until all the tokens in the string have been returned.

On the initial call to wcstok(), the function first searches the wide-character string pointed to by the ws1 parameter to locate the first wide character that does not occur in the wide-character delimiter string pointed to by the ws2 parameter. If such a wide character is found, it is the start of the first token. The wcstok() function then searches from there for a wide character that does occur in the delimiter string. If such a wide-character delimiter is found, wcstok() overwrites it with a null wide character, which terminates the current token. The wcstok() function saves a pointer to the wide character following the null wide character and returns a pointer to the start of the token.

In subsequent calls to wcstok(), where ws1 is set to a null pointer, the function starts at the saved pointer and searches for the next wide character that does not occur in the wide-character delimiter string pointed to by the ws2 parameter. If such a wide character is found, it is the start of the new token. The wcstok() function then searches from there for a wide character that does occur in the delimiter string. If such a wide-character delimiter is found, wcstok() overwrites it with a null wide character, which terminates the new token. The wcstok() function saves a pointer to the wide character following the null wide character and returns a pointer to the start of the new token.

[ISO C]  On successful completion, the wcstok() function stores the saved pointer in the *savept parameter as well as internally. On calls where the s1 parameter is a null pointer, the function uses the saved pointer in *savept to start searching for the next token. Applications that require threadsafe operation must use the wcstok() interface that includes the savept parameter.

If a call to the wcstok() function cannot find a wide character that does not occur in the delimiter string, it returns the null pointer. If a call to the wcstok() function cannot find the terminating wide character that does occur in the delimiter string, the current token extends to the end of the string and subsequent calls to wcstok() return the null pointer.

If the delimiters used in the wide-character string change from one set of characters to another within the string, the application can set the second parameter, ws2, to different wide-character strings from call to call.

The implementation behaves as though no function calls the wcstok() function.

[Digital]  The wcstok_r() function is a reentrant version of wcstok() but is proprietary; new applications that require standards conformance along with threadsafe operation should use the wcstok() interface with the savept parameter rather than the wcstok_r() interface.  

EXAMPLES

The following example splits a wide-character string into tokens:

#include <wchar.h> #include <locale.h> #include <stdio.h> #define WLENGTH 40

main() {
   wchar_t WCString1[WLENGTH], delimiters[WLENGTH];
   wchar_t * pwcs;
   int   counter;


   (void)setlocale(LC_ALL, "");
   printf("Enter the string to be searched: ");
   if (fgetws(WCString1, WLENGTH, stdin) != NULL) {
      printf("Enter the delimiter(s): ");
      if (fgetws(delimiters, WLENGTH, stdin) \ != NULL) {


         if ((pwcs = wcstok(WCString1, delimiters )) \ != NULL) {
            /* pwcs points to the first token */
            printf("Token 1 is %S\n", pwcs);
            counter = 2;
            while ((pwcs = wcstok((wchar_t * )NULL, delimiters )) \ != NULL) {
               printf("Token %d is %S\n", counter, pwcs);
               counter++;
            }
         }
      }
   } }  

RETURN VALUES

On successful completion, the wcstok() function returns a pointer to the first wide character of a token. A null pointer is returned if there is no token.

[ISO C]  The wcstok() function also sets the pointer *savept to the wide character from which the search for the next token starts, or to a null pointer if there is none.

[Digital]  On successful completion, the wcstok_r() returns a pointer to the first wide character of a token. A null pointer is returned if there is no token. The function also sets the pointer *savept to the wide character from which the search for the next token starts, or to a null pointer if there is none.  

RELATED INFORMATION

Functions: strtok(3), wcspbrk(3), wcsspn(3), wcstod(3), wcstol(3), wcstoul(3)

Standards: standards(5) delim off


 

Index

NAME
LIBRARY
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
EXAMPLES
RETURN VALUES
RELATED INFORMATION

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Time: 02:41:57 GMT, October 02, 2010