環境：Win10、VS2017

一、生成C++動態連結庫dll

1. 建立動態連結庫dll

2. 新建一個C++類

3. 開啟FourArith.cpp檔案，新增四則運算方法

4. 生成解決方案，編譯生成dll

二、使用C#控制檯應用呼叫上述生成的.dll

1. 新建控制檯應用

2. 為了方便呼叫dll，把MyDll.dll複製到\bin\Debug目錄下。

3. 呼叫MyDll.dll的方法

 1         [DllImport("MyDll.dll", EntryPoint = "Add", CallingConvention = CallingConvention.Cdecl)]
 
 2         public static extern double Add(double a, double b);
 3         [DllImport("MyDll.dll", EntryPoint = "Sub", CallingConvention = CallingConvention.Cdecl)]
 4         public static extern double Sub(double a, double b);
 5         [DllImport("MyDll.dll", EntryPoint = "Multi", CallingConvention = CallingConvention.Cdecl)]
 
 6         public static extern double Multi(double a, double b);
 7         [DllImport("MyDll.dll", EntryPoint = "Divi", CallingConvention = CallingConvention.Cdecl)]
 8         public static extern double Divi(double a, double b);
 9 
10         static void Main(string[] args)
11         {
12             double
 
 a = 2;
13             double b = 3;
14 
15             Console.WriteLine(Add(a, b));
16             Console.WriteLine(Sub(a, b));
17             Console.WriteLine(Multi(a, b));
18             Console.WriteLine(Divi(a, b));
19             Console.ReadKey();
20         }

4. 執行檢視效果