Re: 32b long int???????

[Steve Baker <sjbaker1@airmail.net>]

Felix Kollmann wrote:
> 
> Hi,
> 
> I need a 64b number but int and long are just 32b.
> But long should be 64b.

No - all that C/C++ guarantees is that a long is no shorter
than an int.

Some compilers support  "long long int x ;"

Some compilers *do* produce 64 bits for a 'long int'. (eg SGI's
IRIX C compiler will do that if you build 'n64' format binaries).

> How can I get a 64b long?
> 
> Perhaps:        long test[2] ?

Well - yes - but you can't treat 'test' as a simple number and do
math on it and such. You'd have to write code like:

void increment_64bit ( unsigned int test[2] )
{
  if ( test[0] == 0xFFFFFFFF )
  {
    test[0]=0;
    test[1]++ ;
  }
  else
    test[0]++ ;
}


There really isn't a reliable/portable way to guarantee 64 bit
arithmetic in C/C++. 

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