How can I discover whether my CPU is 32 or 64 bits?

Question

How do I find out if my processor is 32 bit or 64 bit (in your language of choice)? I want to know this for both Intel and AMD processors.

Answer 1

Windows, C/C++:

#include <windows.h>

SYSTEM_INFO sysInfo, *lpInfo;
lpInfo = &sysInfo;
::GetSystemInfo(lpInfo);
switch (lpInfo->wProcessorArchitecture) {
case PROCESSOR_ARCHITECTURE_AMD64:
case PROCESSOR_ARCHITECTURE_IA64:
    // 64 bit
    break;
case PROCESSOR_ARCHITECTURE_INTEL:
    // 32 bit
    break;
case PROCESSOR_ARCHITECTURE_UNKNOWN:
default:
    // something else
    break;
}

Answer 2

C#, OS agnostic

sizeof(IntPtr) == 4 ? "32-bit" : "64-bit"

This is somewhat crude but basically tells you whether the CLR is running as 32-bit or 64-bit, which is more likely what you would need to know. The CLR can run as 32-bit on a 64-bit processor, for example.

For more information, see here: How to detect Windows 64-bit platform with .NET?