mirror of https://github.com/mkerrisk/man-pages
106 lines
3.1 KiB
Groff
106 lines
3.1 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 18:11:47 1993 by Rik Faith (faith@cs.unc.edu)
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.\" 2007-06-15, Marc Boyer <marc.boyer@enseeiht.fr> + mtk
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.\" Improve discussion of strncat().
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.TH STRCAT 3 2008-06-13 "GNU" "Linux Programmer's Manual"
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.SH NAME
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strcat, strncat \- concatenate two strings
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.SH SYNOPSIS
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.nf
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.B #include <string.h>
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.sp
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.BI "char *strcat(char *" dest ", const char *" src );
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.sp
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.BI "char *strncat(char *" dest ", const char *" src ", size_t " n );
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.fi
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.SH DESCRIPTION
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The
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.BR strcat ()
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function appends the \fIsrc\fP string to the
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\fIdest\fP string, overwriting the null byte (\(aq\\0\(aq) at the end of
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\fIdest\fP, and then adds a terminating null byte.
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The strings may not overlap, and the \fIdest\fP string must have
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enough space for the result.
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.PP
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The
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.BR strncat ()
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function is similar, except that
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.IP * 3
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it will use at most \fIn\fP characters from \fIsrc\fP; and
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.IP *
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\fIsrc\fP does not need to be null terminated if it contains
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\fIn\fP or more characters.
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.PP
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As with
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.BR strcat (),
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the resulting string in \fIdest\fP is always null terminated.
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.PP
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If \fIsrc\fP contains \fIn\fP or more characters,
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.BR strncat ()
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writes \fIn+1\fP characters to \fIdest\fP (\fIn\fP
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from \fIsrc\fP plus the terminating null byte).
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Therefore, the size of \fIdest\fP must be at least
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\fIstrlen(dest)+n+1\fP.
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A simple implementation of
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.BR strncat ()
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might be:
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.in +4n
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.nf
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char*
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strncat(char *dest, const char *src, size_t n)
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{
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size_t dest_len = strlen(dest);
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size_t i;
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for (i = 0 ; i < n && src[i] != \(aq\\0\(aq ; i++)
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dest[dest_len + i] = src[i];
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dest[dest_len + i] = \(aq\\0\(aq;
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return dest;
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}
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.fi
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.in
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.SH "RETURN VALUE"
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The
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.BR strcat ()
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and
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.BR strncat ()
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functions return a pointer to the resulting string \fIdest\fP.
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, C89, C99.
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.SH "SEE ALSO"
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.BR bcopy (3),
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.BR memccpy (3),
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.BR memcpy (3),
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.BR strcpy (3),
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.BR strncpy (3),
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.BR wcscat (3),
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.BR wcsncat (3)
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