strtok

Name

strtok, strtok_r
- string tokens

Library

libc.lib

Synopsis

#include <string.h>

char * strtok (char *str, const char *sep);

char * strtok_r (char *str, const char *sep, char **last);

Return values

strtok function returns a pointer to the next token, or NULL if there are no more tokens.

Detailed description

This interface is obsoleted by strsep.

The strtok function is used to isolate sequential tokens in a null-terminated string, str. These tokens are separated in the string by at least one of the characters in sep. The first time that strtok is called, str should be specified; subsequent calls, wishing to obtain further tokens from the same string, should pass a null pointer instead. The separator string, sep, must be supplied each time, and may change between calls.

The implementation will behave as if no library function calls strtok.

The strtok_r function is a reentrant version of strtok. The context pointer last must be provided on each call. The strtok_r function may also be used to nest two parsing loops within one another, as long as separate context pointers are used.

The strtok and strtok_r functions return a pointer to the beginning of each subsequent token in the string, after replacing the token itself with a NUL character. When no more tokens remain, a null pointer is returned.

Examples

#include <string.h>
#include <stdio.h>
int main()
{
    char one[50];
    char *res;
    strcpy(one,"Hello,World,Hi");
    res=strtok(one,",");
    if(!strcmp(res,"Hello"))
    printf("%s\n",res);
    res=strtok(NULL,",");
    if(!strcmp(res,"World"))
    printf("%s\n",res);
    return 0;
}

Output

Hello
World

Bugs

The System V strtok, if handed a string containing only delimiter characters, will not alter the next starting point, so that a call to strtok with a different (or empty) delimiter string may return a non- NULL value. Since this implementation always alters the next starting point, such a sequence of calls would always return NULL.

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