On Mon, 2005-04-04 at 12:20 -0400, Brian Weaver wrote:
> Since a 'double' and a 'long long' are both the same number of bytes.
> You could do something like:
>
> unsigned long long htonll(unsigned long long in)
> {
> register unsigned long hold;
> register unsigned long *p = (unsigned long *)∈
> register unsigned long *q = p + 1;
>
> *p = htonl(*p);
> *q = htonl(*q);
> hold = *p;
> *p = *q;
> *q = hold;
>
> return in;
> }
The above looks like it will work on some machines, but IT IS NOT 64-bit
CLEAN AND THUS YOU SHOULD AVOID IT !!! For instance, try:
cat > tst.c <<EOFF
#include "stdio.h"
int main (int argc, char ** argv)
{
printf("sizeof(long) = %d\n",sizeof(long));
printf("sizeof(unsigned long) = %d\n",sizeof(unsigned long));
return 0;
}
EOF
make tst
./tst
on AMD64 (x86_64) system and see why.
In any case, as long as both machines are using IEEE-754 representations
(which basically everyone is) you don't have to worry about the mantissa
and exponent, you just have to swap the bytes:
01234567 ==> 76543210
Ed
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