C# Signature:

[DllImport("kernel32.dll")]
static extern void GetSystemInfo(out SYSTEM_INFO lpSystemInfo);

VB.Net Signature:

Private Declare Sub GetSystemInfo Lib "kernel32" (<MarshalAs(UnmanagedType.Struct)> ByRef lpSystemInfo As SYSTEM_INFO)

User-Defined Types:

SYSTEM_INFO

Notes:

This API mapping demonstrates mapping a union in C#.

Tips & Tricks:

The lpMinimumApplicationAddress, lpMaximumApplicationAddress, dwActiveProcessorMask are pointers in kernal32.dll, so the size changes when used from within a 64-bit application. If you need to use these, you will have to cast them to either an uint or a ulong.

Sample Code:

using System;
using System.Runtime.InteropServices;

namespace TestGetSystemInfo
{
    public class WinApi
    {
    [DllImport("kernel32.dll")]
    public static extern void GetSystemInfo([MarshalAs(UnmanagedType.Struct)] ref SYSTEM_INFO lpSystemInfo);

    [StructLayout(LayoutKind.Sequential)]
    public struct SYSTEM_INFO
    {
        internal _PROCESSOR_INFO_UNION uProcessorInfo;
        public uint dwPageSize;
        public IntPtr lpMinimumApplicationAddress;
        public IntPtr lpMaximumApplicationAddress;
        public IntPtr dwActiveProcessorMask;
        public uint dwNumberOfProcessors;
        public uint dwProcessorType;
        public uint dwAllocationGranularity;
        public ushort dwProcessorLevel;
        public ushort dwProcessorRevision;
    }

    [StructLayout(LayoutKind.Explicit)]
    public struct _PROCESSOR_INFO_UNION
    {
        [FieldOffset(0)]
        internal uint dwOemId;
        [FieldOffset(0)]
        internal ushort wProcessorArchitecture;
        [FieldOffset(2)]
        internal ushort wReserved;
    }
    }

    public class Program
    {
    public static void Main(string[] args)
    {
        WinApi.SYSTEM_INFO sysinfo = new WinApi.SYSTEM_INFO();
        WinApi.GetSystemInfo(ref sysinfo);
        Console.WriteLine("dwProcessorType ={0}", sysinfo.dwProcessorType.ToString());
        Console.WriteLine("dwPageSize      ={0}", sysinfo.dwPageSize.ToString());
    }
    }
}

Determinating CPU Version:

    public enum eOperatingSystem
    {
        X64,
        x86,
        Itanium,
        Unknown
    }

    public eOperatingSystem DeterminateOperatingSystemFlavor()
    {
        // http://msdn2.microsoft.com/en-us/library/ms724958.aspx

        eOperatingSystem result = eOperatingSystem.Unknown;
        try
        {
        SYSTEM_INFO l_System_Info = new SYSTEM_INFO();
        GetSystemInfo(ref l_System_Info);

        switch (l_System_Info.uProcessorInfo.wProcessorArchitecture)
        {
            case 9: // PROCESSOR_ARCHITECTURE_AMD64
            result = eOperatingSystem.X64;
            break;
            case 6: // PROCESSOR_ARCHITECTURE_IA64
            result = eOperatingSystem.Itanium;
            break;
            case 0: // PROCESSOR_ARCHITECTURE_INTEL
            result = eOperatingSystem.x86;
            break;
            default: // PROCESSOR_ARCHITECTURE_UNKNOWN
            result = eOperatingSystem.Unknown;
            break;
        }
        }
        catch
        {
        // Ignore        
        }

        return result;

    }

    // Remark: This is not just for compile time, but as well as runtime. If you have a 64bit OS, and this was compiled on 32Bit, it will return .X64
    public eOperatingSystem DeterminateCompileFlavor()
    {
        if (System.IntPtr.Size == 8)
        return eOperatingSystem.X64;
        else
        return eOperatingSystem.x86;
    }
    // NOTE: The above code snippet DOES NOT WORK when running with the 32-bit CLR on a 64-bit machine;
    //   it will ALWAYS report .Size == 32 (because the 32-bit CLR is working in 32-bit mode on the
    //   64-bit machine).  Therefore, you must use the more extensive code above.

Alternative Managed API:

Do you know one? Please contribute it!

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).