C#通过WinAPI获取内存信息，32位64位可用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace ConsoleGetSysMemory
{
class Program
{
[StructLayout(LayoutKind.Sequential)]
public struct MEMORYSTATUSEX
{
public uint dwLength;
public uint dwMemoryLoad;
public ulong ullTotalPhys;
public ulong ullAvailPhys; //可用物理内存
public ulong ullTotalPageFile;
public ulong ullAvailPageFile;
public ulong ullTotalVirtual;
public ulong ullAvailVirtual;
public ulong ullAvailExtendedVirtual;
}

[DllImport("kernel32.dll")]
public static extern void GlobalMemoryStatusEx(ref MEMORYSTATUSEX stat);

static void Main(string[] args)
{
string msg = "物理内存总数:{1}Mb{0}可用物理内存:{2}Mb{0}虚拟内存总数:{3}Mb{0}可用虚拟内存:{4}Mb";

MEMORYSTATUSEX memInfo = new MEMORYSTATUSEX();
memInfo.dwLength = (uint)Marshal.SizeOf(typeof(MEMORYSTATUSEX));

GlobalMemoryStatusEx(ref memInfo);

Console.WriteLine(string.Format(msg,
Environment.NewLine,
memInfo.ullTotalPhys / 1024 / 1024,
memInfo.ullAvailPhys / 1024 / 1024,
memInfo.ullTotalVirtual / 1024 / 1024,
memInfo.ullAvailVirtual / 1024 / 1024));

Console.ReadKey();
}
}
}

也可以用另一个API GlobalMemoryStatus获取上述信息，但该方法参数长度在32位和64位系统下不同，如定义错误拿不到正确值，如下：

32位系统

[StructLayout(LayoutKind.Sequential)]
public struct MemoryStatus
{
public uint Length;
public uint MemoryLoad;
public uint TotalPhysical;
public uint AvailablePhysical;//可用物理内存
public uint TotalPageFile;
public uint AvailablePageFile;
public uint TotalVirtual;
public uint AvailableVirtual;
}

MemoryStatus memStatus = new MemoryStatus();
memStatus.Length = (uint)Marshal.SizeOf(typeof(MemoryStatus));

GlobalMemoryStatus(ref memStatus);

Console.WriteLine(string.Format(msg,
Environment.NewLine,
memStatus.TotalPhysical / 1024 / 1024,
memStatus.AvailablePhysical / 1024 / 1024,
memStatus.TotalVirtual / 1024 / 1024,
memStatus.AvailableVirtual / 1024 / 1024));

64位系统

[StructLayout(LayoutKind.Sequential)]
public struct MemoryStatus
{
public uint Length;
public uint MemoryLoad;
public ulong TotalPhysical;
public ulong AvailablePhysical;//可用物理内存
public ulong TotalPageFile;
public ulong AvailablePageFile;
public ulong TotalVirtual;
public ulong AvailableVirtual;
}

MemoryStatus memStatus = new MemoryStatus();
memStatus.Length = (uint)Marshal.SizeOf(typeof(MemoryStatus));

GlobalMemoryStatus(ref memStatus);

Console.WriteLine(string.Format(msg,
Environment.NewLine,
(long)memStatus.TotalPhysical / 1024 / 1024,
(long)memStatus.AvailablePhysical / 1024 / 1024,
(long)memStatus.TotalVirtual / 1024 / 1024,
(long)memStatus.AvailableVirtual / 1024 / 1024));