.\" part of publib
.\" "@(#)publib-strutil:$Id: memswap.3,v 1.1.1.1 1994/02/03 17:25:30 liw Exp $"
.\"
.TH MEMSWAP 3 "C Programmer's Manual" Publib "C Programmer's Manual"
.SH NAME
memswap \- swap the contents of two memory blocks
.SH SYNOPSIS
.nf
#include <publib.h>
void \fBmemswap\fR(void *\fIblock1\fR, void *\fIblock2\fR, size_t \fIn\fR);
.SH DESCRIPTION
\fImemswap\fR will swap the contents of the two blocks pointed by
its first two arguments.  The last argument gives the size of the
memory blocks.
.SH EXAMPLE
To swap two structs, one might do the following.
.sp 1
.nf
.in +5
struct tm tm1, tm2;

memswap(&tm1, &tm2, sizeof(struct tm));
.in -5
.SH BUGS
Using \fImemswap\fR to swap small portions of memory is inefficient.
It is not worth it to use it to swap variables of any of the basic
types, for instance.  Use inline code for such cases.  However, for
large portions of memory, e.g., arrays, it is convenient.
.PP
\fImemswap\fR can't swap variables whose address can't be taken.  This
excludes variables with the \fBregister\fR specifier and bitfields in
structs.  But then, there is no way to write a function (or macro) that
can handle any kind of arguments.  Life is hard.
.SH "SEE ALSO"
publib(3)
.SH AUTHOR
Lars Wirzenius (lars.wirzenius@helsinki.fi)