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+.\" Copyright (c) 1990, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     $OpenBSD: strcspn.3,v 1.9 2007/08/08 07:20:45 ray Exp $
+.\"
+.Dd $Mdocdate: August 8 2007 $
+.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
+.Sh STANDARDS
+The
+.Fn strcspn
+function conforms to
+.St -ansiC .