string/FreeBSD/strtok.3

   1 .\" Copyright (c) 1998 Softweyr LLC.  All rights reserved.
   2 .\"
   3 .\" strtok_r, from Berkeley strtok
   4 .\" Oct 13, 1998 by Wes Peters <wes@softweyr.com>
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  50 .\"     @(#)strtok.3    8.2 (Berkeley) 2/3/94
  51 .\" $FreeBSD: src/lib/libc/string/strtok.3,v 1.24 2002/12/18 12:45:11 ru Exp $
  52 .\"
  53 .Dd November 27, 1998
  54 .Dt STRTOK 3
  55 .Os
  56 .Sh NAME
  57 .Nm strtok , strtok_r
  58 .Nd string tokens
  59 .Sh LIBRARY
  60 .Lb libc
  61 .Sh SYNOPSIS
  62 .In string.h
  63 .Ft char *
  64 .Fn strtok "char *str" "const char *sep"
  65 .Ft char *
  66 .Fn strtok_r "char *str" "const char *sep" "char **last"
  67 .Sh DESCRIPTION
  68 .Bf -symbolic
  69 This interface is obsoleted by
  70 .Xr strsep 3 .
  71 .Ef
  72 .Pp
  73 The
  74 .Fn strtok
  75 function
  76 is used to isolate sequential tokens in a null-terminated string,
  77 .Fa str .
  78 These tokens are separated in the string by at least one of the
  79 characters in
  80 .Fa sep .
  81 The first time that
  82 .Fn strtok
  83 is called,
  84 .Fa str
  85 should be specified; subsequent calls, wishing to obtain further tokens
  86 from the same string, should pass a null pointer instead.
  87 The separator string,
  88 .Fa sep ,
  89 must be supplied each time, and may change between calls.
  90 .Pp
  91 The implementation will behave as if no library function calls
  92 .Fn strtok .
  93 .Pp
  94 The
  95 .Fn strtok_r
  96 function is a reentrant version of
  97 .Fn strtok .
  98 The context pointer
  99 .Fa last
 100 must be provided on each call.
 101 The
 102 .Fn strtok_r
 103 function
 104 may also be used to nest two parsing loops within one another, as
 105 long as separate context pointers are used.
 106 .Pp
 107 The
 108 .Fn strtok
 109 and
 110 .Fn strtok_r
 111 functions
 112 return a pointer to the beginning of each subsequent token in the string,
 113 after replacing the token itself with a
 114 .Dv NUL
 115 character.
 116 When no more tokens remain, a null pointer is returned.
 117 .Sh EXAMPLES
 118 The following uses
 119 .Fn strtok_r
 120 to parse two strings using separate contexts:
 121 .Bd -literal
 122 char test[80], blah[80];
 123 char *sep = "\e\e/:;=-";
 124 char *word, *phrase, *brkt, *brkb;
 125
 126 strcpy(test, "This;is.a:test:of=the/string\e\etokenizer-function.");
 127
 128 for (word = strtok_r(test, sep, &brkt);
 129      word;
 130      word = strtok_r(NULL, sep, &brkt))
 131 {
 132     strcpy(blah, "blah:blat:blab:blag");
 133
 134     for (phrase = strtok_r(blah, sep, &brkb);
 135          phrase;
 136          phrase = strtok_r(NULL, sep, &brkb))
 137     {
 138         printf("So far we're at %s:%s\en", word, phrase);
 139     }
 140 }
 141 .Ed
 142 .Sh SEE ALSO
 143 .Xr memchr 3 ,
 144 .Xr strchr 3 ,
 145 .Xr strcspn 3 ,
 146 .Xr strpbrk 3 ,
 147 .Xr strrchr 3 ,
 148 .Xr strsep 3 ,
 149 .Xr strspn 3 ,
 150 .Xr strstr 3 ,
 151 .Xr wcstok 3
 152 .Sh STANDARDS
 153 The
 154 .Fn strtok
 155 function
 156 conforms to
 157 .St -isoC .
 158 .Sh BUGS
 159 The System V
 160 .Fn strtok ,
 161 if handed a string containing only delimiter characters,
 162 will not alter the next starting point, so that a call to
 163 .Fn strtok
 164 with a different (or empty) delimiter string
 165 may return a
 166 .Pf non- Dv NULL
 167 value.
 168 Since this implementation always alters the next starting point,
 169 such a sequence of calls would always return
 170 .Dv NULL .
 171 .Sh AUTHORS
 172 .An Wes Peters ,
 173 Softweyr LLC:
 174 .Aq wes@softweyr.com
 175 .Pp
 176 Based on the
 177 .Fx 3.0
 178 implementation.