.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 17:57:50 1993 by Rik Faith (faith@cs.unc.edu)
.TH STRSPN 3 2021-03-22 GNU "Linux Programmer's Manual"
.SH NAME
strspn, strcspn \- get length of a prefix substring
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <string.h>
.PP
.BI "size_t strspn(const char *" s ", const char *" accept );
.BI "size_t strcspn(const char *" s ", const char *" reject );
.fi
.SH DESCRIPTION
The
.BR strspn ()
function calculates the length (in bytes) of the initial
segment of
.I s
which consists entirely of bytes in
.IR accept .
.PP
The
.BR strcspn ()
function calculates the length of the initial
segment of
.I s
which consists entirely of bytes not in
.IR reject .
.SH RETURN VALUE
The
.BR strspn ()
function returns the number of bytes in
the initial segment of
.I s
which consist only of bytes
from
.IR accept .
.PP
The
.BR strcspn ()
function returns the number of bytes in
the initial segment of
.I s
which are not in the string
.IR reject .
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR strspn (),
.BR strcspn ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
.SH SEE ALSO
.BR index (3),
.BR memchr (3),
.BR rindex (3),
.BR strchr (3),
.BR string (3),
.BR strpbrk (3),
.BR strsep (3),
.BR strstr (3),
.BR strtok (3),
.BR wcscspn (3),
.BR wcsspn (3)