. NET Framework uses Unmanaged DLL Functions

Today, on the MSDN of tw, I suddenly saw c # Call the dll compiled by c. The method is good. simple. active X is still written in the past, which is troublesome. for more information, see MSDN (v2005 ).

using System;using System.Runtime.InteropServices;class MainClass {    [DllImport("User32.dll")]    public static extern int MessageBox(int h, string m, string c, int type);    static int Main()     {        string myString;         Console.Write("Enter your message: ");        myString = Console.ReadLine();        return MessageBox(0, myString, "My Message Box", 0);    }}

Description
This example creates an external DLL that will be called from the C # program in Example 3.
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// cmdll.c// compile with: /LD /MDint __declspec(dllexport) SampleMethod(int i){    return i*10;}
 
   
 
  
 
 
 
This example uses two filesCM.csAndCmdll.cTo describe extern. The C file is the external DLL created in example 2, which is called from the C # program.
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// cm.csusing System;using System.Runtime.InteropServices;public class MainClass {    [DllImport("Cmdll.dll")]    public static extern int SampleMethod(int x);    static void Main()     {        Console.WriteLine("SampleMethod() returns {0}.",                 SampleMethod(5));    }}
 
   
 
  
 
 
Refer:
Extern (C # reference)
Ms-help: // MS. MSDNQTR. v80.chs/MS. MSDN. v80/MS. VisualStudio. v80.chs/dv_csref/html/9c3f02c4-51b8-4d80-9cb2-f2b6e1ae15c7.htm
DllImportAttribute class
Ms-help: // MS. MSDNQTR. v80.chs/MS. MSDN. v80/MS. NETDEVFX. v1_chs/cpref11/html/T_System_Runtime_InteropServices_DllImportAttribute.htm
Use Unmanaged DLL Functions
Ms-help: // MS. MSDNQTR. v80.chs/MS. MSDN. v80/MS. VisualStudio. v80.chs/dv_fxinterop/html/eca7606e-ebfb-4f47-b8d9-289903fdc045.htm