freebsd-dev/lib/libc/string/strsep.3
Ed Maste 0eff530775 strsep.3: don't silently ignore errors
Reported by:	bde
MFC with:	r334275
2018-05-28 18:29:15 +00:00

136 lines
3.7 KiB
Groff

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.\" @(#)strsep.3 8.1 (Berkeley) 6/9/93
.\" $FreeBSD$
.\"
.Dd May 28, 2018
.Dt STRSEP 3
.Os
.Sh NAME
.Nm strsep
.Nd separate strings
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In string.h
.Ft char *
.Fn strsep "char **stringp" "const char *delim"
.Sh DESCRIPTION
The
.Fn strsep
function locates, in the string referenced by
.Fa *stringp ,
the first occurrence of any character in the string
.Fa delim
(or the terminating
.Ql \e0
character) and replaces it with a
.Ql \e0 .
The location of the next character after the delimiter character
(or NULL, if the end of the string was reached) is stored in
.Fa *stringp .
The original value of
.Fa *stringp
is returned.
.Pp
An
.Dq empty
field (i.e., a character in the string
.Fa delim
occurs as the first character of
.Fa *stringp )
can be detected by comparing the location referenced by the returned pointer
to
.Ql \e0 .
.Pp
If
.Fa *stringp
is initially
.Dv NULL ,
.Fn strsep
returns
.Dv NULL .
.Sh EXAMPLES
The following uses
.Fn strsep
to parse a string, and prints each token in separate line:
.Bd -literal -offset indent
char *token, *string, *tofree;
tofree = string = strdup("abc,def,ghi");
if (string == NULL)
err(1, "strdup");
while ((token = strsep(&string, ",")) != NULL)
printf("%s\en", token);
free(tofree);
.Ed
.Pp
The following uses
.Fn strsep
to parse a string, containing tokens delimited by white space, into an
argument vector:
.Bd -literal -offset indent
char **ap, *argv[10], *inputstring;
for (ap = argv; (*ap = strsep(&inputstring, " \et")) != NULL;)
if (**ap != '\e0')
if (++ap >= &argv[10])
break;
.Ed
.Sh SEE ALSO
.Xr memchr 3 ,
.Xr strchr 3 ,
.Xr strcspn 3 ,
.Xr strpbrk 3 ,
.Xr strrchr 3 ,
.Xr strspn 3 ,
.Xr strstr 3 ,
.Xr strtok 3
.Sh HISTORY
The
.Fn strsep
function
is intended as a replacement for the
.Fn strtok
function.
While the
.Fn strtok
function should be preferred for portability reasons (it conforms to
.St -isoC )
it is unable to handle empty fields, i.e., detect fields delimited by
two adjacent delimiter characters, or to be used for more than a single
string at a time.
The
.Fn strsep
function first appeared in
.Bx 4.4 .