.\" Copyright (c) 1988, 1991 The Regents of the University of California. .\" All rights reserved. .\" .\" This code is derived from software contributed to Berkeley by .\" the American National Standards Committee X3, on Information .\" Processing Systems. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $OpenBSD: strtok.3,v 1.17 2004/01/20 06:06:48 millert Exp $ .\" .Dd June 29, 1991 .Dt STRTOK 3 .Os .Sh NAME .Nm strtok , .Nm strtok_r .Nd string token operations .Sh SYNOPSIS .Fd #include <string.h> .Ft char * .Fn strtok "char *str" "const char *sep" .Ft char * .Fn strtok_r "char *str" "const char *sep" "char **last" .Sh DESCRIPTION .Bf -symbolic This interface is obsoleted by .Xr strsep 3 . .Ef .Pp The .Fn strtok function is used to isolate sequential tokens in a null-terminated string, .Fa str . These tokens are separated in the string by at least one of the characters in .Fa sep . The first time that .Fn strtok is called, .Fa str should be specified; subsequent calls, wishing to obtain further tokens from the same string, should pass a null pointer instead. The separator string, .Fa sep , must be supplied each time, and may change between calls. .Pp The .Fn strtok_r function is a version of .Fn strtok that takes an explicit context argument and is reentrant. .Pp The .Fn strtok and .Fn strtok_r functions return a pointer to the beginning of each subsequent token in the string, after replacing the separator character itself with an .Tn ASCII NUL character. When no more tokens remain, a null pointer is returned. .Pp Since .Fn strtok and .Fn strtok_r modify the string, .Fa str should not point to an area in the initialized data segment. .Sh EXAMPLES The following will construct an array of pointers to each individual word in the string .Va s : .Bd -literal -offset indent #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))) { if (i < MAXTOKENS - 1) tokens[i++] = p; } tokens[i] = NULL; .Ed .Pp That is, .Li tokens[0] will point to .Qq cat , .Li tokens[1] will point to .Qq dog , .Li tokens[2] will point to .Qq horse , and .Li tokens[3] will point to .Qq cow . .Sh SEE ALSO .Xr memchr 3 , .Xr strchr 3 , .Xr strcspn 3 , .Xr strpbrk 3 , .Xr strrchr 3 , .Xr strsep 3 , .Xr strspn 3 , .Xr strstr 3 .Sh STANDARDS The .Fn strtok function conforms to .St -ansiC . .Sh BUGS The System V .Fn strtok , if handed a string containing only delimiter characters, will not alter the next starting point, so that a call to .Fn 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 .Dv NULL .