C#调用dll代码范例

public class ExecuteDLL : Form
{
   private IntPtr hModule = IntPtr.Zero;
   //申明外部API
   [DllImport("kernel32.dll")]
   static extern IntPtr LoadLibrary(string lpFileName);
   [DllImport("kernel32.dll")]
   static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);
   [DllImport("kernel32", EntryPoint = "FreeLibrary", SetLastError = true)]
   static extern bool FreeLibrary(IntPtr hModule);
   //申明委托
   private delegate IntPtr TestFunc(int window);
   private void test()
   {
        string strDLLPath =  ".\\tests.dll";
        hModule = LoadLibrary(strDLLPath);
        if (hModule.Equals(IntPtr.Zero))
        {
            MessageBox.Show("导入DLL失败");
            return;
        }
       TestFuncfarProc = (TestFunc)this.GetFunctionAddress(hModule, "TestFunc", typeof(TestFunc));
       if (farProc == null)
       {
           FreeLibrary(hModule);
           hModule = IntPtr.Zero;
           return;
       }
       //利用委托执行DLL文件中的接口方法
       farProc(hModule, IntPtr.Zero, IntPtr.Zero, null, null, strNo);
       FreeLibrary(hModule);
       hModule = IntPtr.Zero;
   }
}