long long implementation in 32 bit machine

Question

As per c99 standard, size of long long should be minimum 64 bits. How is this implemented in a 32 bit machine (eg. addition or multiplication of 2 long lo

Answer 1

The next C++ standard (due 2009, or maybe 2010), is slated to include the "long long" type. As mentioned earlier, it's already in common use.

The implementation is up to the compiler writers, although computers have always supported multiple precision operations. Some languages, like Python and Common Lisp, require support for indefinite-precision integers. Long ago, I wrote 64-bit multiplication and division routines for a computer (the Z80) that could manage 16-bit addition and subtraction, with no hardware multiplication at all.

Probably the easiest way to see how an operation is implemented on your particular compiler is to write a code sample and examine the assembler output, which is available from all the major compilers I've worked with.