string/FreeBSD/strsep.3

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  31 .\"     @(#)strsep.3    8.1 (Berkeley) 6/9/93
  32 .\" $FreeBSD: src/lib/libc/string/strsep.3,v 1.16 2008/12/05 15:50:59 pjd Exp $
  33 .\"
  34 .Dd December 5, 2008
  35 .Dt STRSEP 3
  36 .Os
  37 .Sh NAME
  38 .Nm strsep
  39 .Nd separate strings
  40 .Sh LIBRARY
  41 .Lb libc
  42 .Sh SYNOPSIS
  43 .In string.h
  44 .Ft char *
  45 .Fn strsep "char **stringp" "const char *delim"
  46 .Sh DESCRIPTION
  47 The
  48 .Fn strsep
  49 function locates, in the string referenced by
  50 .Fa *stringp ,
  51 the first occurrence of any character in the string
  52 .Fa delim
  53 (or the terminating
  54 .Ql \e0
  55 character) and replaces it with a
  56 .Ql \e0 .
  57 The location of the next character after the delimiter character
  58 (or NULL, if the end of the string was reached) is stored in
  59 .Fa *stringp .
  60 The original value of
  61 .Fa *stringp
  62 is returned.
  63 .Pp
  64 An
  65 .Dq empty
  66 field (i.e., a character in the string
  67 .Fa delim
  68 occurs as the first character of
  69 .Fa *stringp )
  70 can be detected by comparing the location referenced by the returned pointer
  71 to
  72 .Ql \e0 .
  73 .Pp
  74 If
  75 .Fa *stringp
  76 is initially
  77 .Dv NULL ,
  78 .Fn strsep
  79 returns
  80 .Dv NULL .
  81 .Sh EXAMPLES
  82 The following uses
  83 .Fn strsep
  84 to parse a string, and prints each token in separate line:
  85 .Bd -literal -offset indent
  86 char *token, *string, *tofree;
  87
  88 tofree = string = strdup("abc,def,ghi");
  89 assert(string != NULL);
  90
  91 while ((token = strsep(&string, ",")) != NULL)
  92         printf("%s\en", token);
  93
  94 free(tofree);
  95 .Ed
  96 .Pp
  97 The following uses
  98 .Fn strsep
  99 to parse a string, containing tokens delimited by white space, into an
 100 argument vector:
 101 .Bd -literal -offset indent
 102 char **ap, *argv[10], *inputstring;
 103
 104 for (ap = argv; (*ap = strsep(&inputstring, " \et")) != NULL;)
 105         if (**ap != '\e0')
 106                 if (++ap >= &argv[10])
 107                         break;
 108 .Ed
 109 .Sh SEE ALSO
 110 .Xr memchr 3 ,
 111 .Xr strchr 3 ,
 112 .Xr strcspn 3 ,
 113 .Xr strpbrk 3 ,
 114 .Xr strrchr 3 ,
 115 .Xr strspn 3 ,
 116 .Xr strstr 3 ,
 117 .Xr strtok 3
 118 .Sh HISTORY
 119 The
 120 .Fn strsep
 121 function
 122 is intended as a replacement for the
 123 .Fn strtok
 124 function.
 125 While the
 126 .Fn strtok
 127 function should be preferred for portability reasons (it conforms to
 128 .St -isoC )
 129 it is unable to handle empty fields, i.e., detect fields delimited by
 130 two adjacent delimiter characters, or to be used for more than a single
 131 string at a time.
 132 The
 133 .Fn strsep
 134 function first appeared in
 135 .Bx 4.4 .