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.TH STRNCPY "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH PROLOG

This manual page is part of the POSIX Programmer's Manual.

The Linux implementation of this interface may differ (consult

the corresponding Linux manual page for details of Linux behavior),

or the interface may not be implemented on Linux.

.SH NAME

stpncpy, strncpy

\(em copy fixed length string, returning a pointer to the array end

.SH SYNOPSIS

.LP

.nf

#include <string.h>

.P

char *stpncpy(char *restrict \fIs1\fP, const char *restrict \fIs2\fP, size_t \fIn\fP);

char *strncpy(char *restrict \fIs1\fP, const char *restrict \fIs2\fP, size_t \fIn\fP);

.fi

.SH DESCRIPTION

For

\fIstrncpy\fR():

The functionality described on this reference page is aligned with the

ISO\ C standard. Any conflict between the requirements described here and the

ISO\ C standard is unintentional. This volume of POSIX.1\(hy2008 defers to the ISO\ C standard.

.P

The

\fIstpncpy\fR()

and

\fIstrncpy\fR()

functions shall copy not more than

.IR n

bytes (bytes that follow a NUL character are not copied) from the array

pointed to by

.IR s2

to the array pointed to by

.IR s1 .

.P

If the array pointed to by

.IR s2

is a string that is shorter than

.IR n

bytes, NUL characters shall be appended to the copy in the array

pointed to by

.IR s1 ,

until

.IR n

bytes in all are written.

.P

If copying takes place between objects that overlap, the behavior is

undefined.

.SH "RETURN VALUE"

If a NUL character is written to the destination, the

\fIstpncpy\fR()

function shall return the address of the first such NUL character.

Otherwise, it shall return

.IR &s1 [ n ].

.P

The

\fIstrncpy\fR()

function shall return

.IR s1 .

.P

No return values are reserved to indicate an error.

.SH ERRORS

No errors are defined.

.LP

.IR "The following sections are informative."

.SH EXAMPLES

None.

.SH "APPLICATION USAGE"

Applications must provide the space in

.IR s1

for the

.IR n

bytes to be transferred, as well as ensure that the

.IR s2

and

.IR s1

arrays do not overlap.

.P

Character movement is performed differently in different

implementations. Thus, overlapping moves may yield surprises.

.P

If there is no NUL character byte in the first

.IR n

bytes of the array pointed to by

.IR s2 ,

the result is not null-terminated.

.SH RATIONALE

None.

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fIstrcpy\fR\^(\|)",

.IR "\fIwcsncpy\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "\fB<string.h>\fP"

.SH COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology

-- Portable Operating System Interface (POSIX), The Open Group Base

Specifications Issue 7, Copyright (C) 2013 by the Institute of

Electrical and Electronics Engineers, Inc and The Open Group.

(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the

event of any discrepancy between this version and the original IEEE and

The Open Group Standard, the original IEEE and The Open Group Standard

is the referee document. The original Standard can be obtained online at

http://www.unix.org/online.html .

Any typographical or formatting errors that appear

in this page are most likely

to have been introduced during the conversion of the source files to

man page format. To report such errors, see

https://www.kernel.org/doc/man-pages/reporting_bugs.html .