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);

}