.\"	$OpenBSD: strcspn.3,v 1.10 2011/07/25 00:38:53 schwarze Exp $
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.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
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.Dd $Mdocdate: July 25 2011 $
.Dt STRCSPN 3
.Os
.Sh NAME
.Nm strcspn
.Nd span the complement of a string
.Sh SYNOPSIS
.Fd #include <string.h>
.Ft size_t
.Fn strcspn "const char *s" "const char *charset"
.Sh DESCRIPTION
The
.Fn strcspn
function spans the initial part of the NUL-terminated string
.Fa s
as long as the characters from
.Fa s
do not occur in string
.Fa charset
(it spans the
.Em complement
of
.Fa charset ) .
.Sh RETURN VALUES
The
.Fn strcspn
function returns the number of characters spanned.
.Sh EXAMPLES
The following call to
.Fn strcspn
will return 3, since the first three characters of string
.Fa s
do not occur in string
.Fa charset :
.Bd -literal -offset indent
char *s = "foobar";
char *charset = "bar";
size_t span;

span = strcspn(s, charset);
.Ed
.Pp
The following removes the first (if any) newline character from string
.Fa line .
This is useful for trimming the newline after a
.Xr fgets 3
call.
.Bd -literal -offset indent
char line[BUFSIZ];

if (fgets(line, sizeof(line), fp) != NULL)
	line[strcspn(line, "\en")] = '\e0';
.Ed
.Sh SEE ALSO
.Xr memchr 3 ,
.Xr strchr 3 ,
.Xr strpbrk 3 ,
.Xr strrchr 3 ,
.Xr strsep 3 ,
.Xr strspn 3 ,
.Xr strstr 3 ,
.Xr strtok 3 ,
.Xr wcscspn 3
.Sh STANDARDS
The
.Fn strcspn
function conforms to
.St -ansiC .
.Sh HISTORY
The
.Fn strcspn
function first appeared in
.At III
and was reimplemented for
.Bx 4.3 Tahoe .