how to find if the machine is 32bit or 64bit

Question

Is there anyway from a C prog to find whether the OS is currently running in 32bit or 64bit mode. I am using a simple program as below

int main(void){
     s         


        

Answer 1

In addition to compile-time methods, and if you are running on Windows: a call to IsWow64Process ( http://msdn.microsoft.com/en-us/library/ms684139.aspx ) will return true if a process is a 32-bit one running under a 64-bit Windows.