1.\" Copyright (c) 1988, 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" $OpenBSD: strtok.3,v 1.15 2001/08/06 10:42:26 mpech Exp $ 37.\" 38.Dd June 29, 1991 39.Dt STRTOK 3 40.Os 41.Sh NAME 42.Nm strtok , 43.Nm strtok_r 44.Nd string token operations 45.Sh SYNOPSIS 46.Fd #include <string.h> 47.Ft char * 48.Fn strtok "char *str" "const char *sep" 49.Ft char * 50.Fn strtok_r "char *str" "const char *sep" "char **last" 51.Sh DESCRIPTION 52.Bf -symbolic 53This interface is obsoleted by 54.Xr strsep 3 . 55.Ef 56.Pp 57The 58.Fn strtok 59function is used to isolate sequential tokens in a null-terminated string, 60.Fa str . 61These tokens are separated in the string by at least one of the 62characters in 63.Fa sep . 64The first time that 65.Fn strtok 66is called, 67.Fa str 68should be specified; subsequent calls, wishing to obtain further tokens 69from the same string, should pass a null pointer instead. 70The separator string, 71.Fa sep , 72must be supplied each time, and may change between calls. 73.Pp 74The 75.Fn strtok_r 76function is a version of 77.Fn strtok 78that takes an explicit context argument and is reentrant. 79.Pp 80The 81.Fn strtok 82and 83.Fn strtok_r 84functions return a pointer to the beginning of each subsequent token 85in the string, after replacing the separator character itself with an 86.Tn ASCII NUL 87character. 88When no more tokens remain, a null pointer is returned. 89.Pp 90Since 91.Fn strtok 92and 93.Fn strtok_r 94modify the string, 95.Fa str 96should not point to an area in the initialized data segment. 97.Sh EXAMPLES 98The following will construct an array of pointers to each individual word in 99the string 100.Va s : 101.Bd -literal -offset indent 102#define MAXTOKENS 128 103 104char s[512], *p, *tokens[MAXTOKENS]; 105char *last; 106int i = 0; 107 108snprintf(s, sizeof(s), "cat dog horse cow"); 109 110for ((p = strtok_r(s, " ", &last)); p; 111 (p = strtok_r(NULL, " ", &last)), i++) { 112 if (i < MAXTOKENS - 1) 113 tokens[i] = p; 114} 115tokens[i] = NULL; 116.Ed 117.Pp 118That is, 119.Li tokens[0] 120will point to 121.Qq cat , 122.Li tokens[1] 123will point to 124.Qq dog , 125.Li tokens[2] 126will point to 127.Qq horse , 128and 129.Li tokens[3] 130will point to 131.Qq cow . 132.Sh SEE ALSO 133.Xr memchr 3 , 134.Xr strchr 3 , 135.Xr strcspn 3 , 136.Xr strpbrk 3 , 137.Xr strrchr 3 , 138.Xr strsep 3 , 139.Xr strspn 3 , 140.Xr strstr 3 141.Sh STANDARDS 142The 143.Fn strtok 144function conforms to 145.St -ansiC . 146.Sh BUGS 147The System V 148.Fn strtok , 149if handed a string containing only delimiter characters, 150will not alter the next starting point, so that a call to 151.Fn strtok 152with a different (or empty) delimiter string 153may return a non-null value. 154Since this implementation always alters the next starting point, 155such a sequence of calls would always return 156.Dv NULL . 157