strtok(3) - NetBSD Manual Pages

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STRTOK(3)               NetBSD Library Functions Manual              STRTOK(3)

strtok, strtok_r -- string tokens
Standard C Library (libc, -lc)
#include <string.h> char * strtok(char * restrict str, const char * restrict sep); char * strtok_r(char *str, const char *sep, char **lasts);
The strtok() function is used to isolate sequential tokens in a nul-ter- minated 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 fur- ther 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 strtok() function returns a pointer to the beginning of each subse- quent token in the string, after replacing the separator character itself with a NUL character. Separator characters at the beginning of the string or at the continuation point are skipped so that zero length tokens are not returned. When no more tokens remain, a null pointer is returned. The strtok_r() function implements the functionality of strtok() but is passed an additional argument, lasts, which points to a user-provided pointer which is used by strtok_r() to store state which needs to be kept between calls to scan the same string; unlike strtok(), it is not neces- sary to limit tokenizing to a single string at a time when using strtok_r().
The following will construct an array of pointers to each individual word in the string s: #define MAXTOKENS 128 char s[512], *p, *tokens[MAXTOKENS]; char *last; int i = 0; snprintf(s, sizeof(s), "cat dog horse cow"); for ((p = strtok_r(s, " ", &last)); p; (p = strtok_r(NULL, " ", &last)), i++) { if (i < MAXTOKENS - 1) tokens[i] = p; } tokens[i] = NULL; That is, tokens[0] will point to "cat", tokens[1] will point to "dog", tokens[2] will point to "horse", and tokens[3] will point to "cow".
index(3), memchr(3), rindex(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3)
The strtok() function conforms to ANSI X3.159-1989 (``ANSI C89''). The strtok_r() function conforms to IEEE Std 1003.1c-1995 (``POSIX.1'').
The System V strtok(), if handed a string containing only delimiter char- acters, 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 start- ing point, such a sequence of calls would always return NULL. NetBSD 9.3 August 11, 2002 NetBSD 9.3
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