C#中动态调用API函数

using System.Runtime.InteropServices;

internal delegate bool Delegate_Beep(uint dwFreq, uint dwDuration);

[DllImport("kernel32.dll")]

internal static extern IntPtr LoadLibrary(string lpLibFileName);

[DllImport("kernel32.dll")]

internal static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);

[DllImport("kernel32.dll")]

internal static extern bool FreeLibrary(IntPtr hLibModule);

private void button1_Click(object sender, EventArgs e)

{

IntPtr vLibraryHandle = LoadLibrary("Kernel32.dll");

IntPtr vProcAddress = GetProcAddress(vLibraryHandle, "Beep");

Delegate_Beep Beep = Marshal.GetDelegateForFunctionPointer(

vProcAddress, typeof(Delegate_Beep)) as Delegate_Beep;

Beep(100, 100);

FreeLibrary(vLibraryHandle);

}