strtok_s, wcstok_s
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Header File
string.h, _str.h
Category
Memory and String Manipulation Routines
Prototype
char *strtok_s(char * _RESTRICT __s1, rsize_t * _RESTRICT __s1max, const char * _RESTRICT __s2, char ** _RESTRICT __ptr);
wchar_t *wcstok_s(wchar_t * _RESTRICT __s1, rsize_t * _RESTRICT __s1max, const wchar_t * _RESTRICT __s2, wchar_t ** _RESTRICT __ptr);
Description
Replaces strtok, _mbstok, wcstok adding security enhancements.
Searches one string for tokens, which are separated by delimiters defined in a second string.
strtok_s considers the string __s1 to consist of a sequence of zero or more text tokens, separated by spans of one or more characters from the separator string __s2.
The first call to strtok_s returns a pointer to the first character of the first token in __s1 and writes a null character into __s1 immediately following the returned token. Subsequent calls with null for the first argument will work through the string __s1 this way, until no tokens remain.
The separator string __s2 can be different from call to call. ptr is used to point to a user-defined char* to store information necessary to continue scanning for other tokens in the same __s1.
If there is a run-time constraint violation, strtok_s does not indirect through the __s1 or __s2 pointers and does not store any value where ptr is pointing to.
Note: Calls to strtok_s cannot be nested with a function call that also uses strtok_s. Doing so causes an endless loop.
Return Value
strtok_s returns a pointer to the first token found in __s1. A NULL pointer is returned when there are no more tokens or there is a run-time constraint violation.
Example
#include <string.h>
#include <stdio.h>
int main(void)
{
unsigned int s1max = 16;
char input[16] = "abc,d";
char *p;
char *ptr = " ";
/* strtok places a NULL terminator
in front of the token, if found */
p = strtok_s(input, &s1max, ",", &ptr);
if (p) printf("%s\n", p);
/* A second call to strtok using NULL
as the first parameter returns a pointer
to the character following the token */
p = strtok_s(NULL, &s1max, ",", &ptr);
if (p) printf("%s\n", p);
return 0;
}
Portability
| POSIX | Win32 | ANSI C | ANSI C++ | |
|---|---|---|---|---|
|
strtok_s |
+ |
+ |
+ |
+ |
|
wcstok_s |
+ |
+ |
+ |