C# calls C++ in two ways: (1) unmanaged calls; (2) managed calls.
First, use the unmanaged class to call the C++ dll.
1. First, create a new project in vs2010, select the win32 application, and set it as a DLL, as shown in the following figure
5. Create a new CPPDLL class on the dllConsoleApplication1 project and write the following code:
usingSystem;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Text;
usingSystem.Runtime.InteropServices; //Must be added, otherwise DllImport will report an error
namespacedllConsoleApplication1
{
classCPPDLL
{
[DllImport("MyDLL.dll", CharSet = CharSet.Ansi)] //Introduce dll and set character set
//[DllImport("MyDLL.dll")] //Can replace the previous code
publicstaticexternintShow();
}
classProgram
{
staticvoidMain(string[] args)
{
CPPDLL.Show();
Console.ReadLine();
}
}
}
6. Running result:
2. Add the Functions.h header file and the Functions.cpp source file to the previous managed DLL project to use the OpenCV library to output and display images.
In Functions.h:
voidshow();
In Functions.cpp:
#include"Functions.h"
#include<opencv2/opencv.hpp>
usingnamespacecv;
voidshow()
{
Mat img = imread("E:\\Gallery\\abc.jpg");
imshow("src",img);
waitKey(0);
}
3. Use C++ managed classes for encapsulation. Added clrClass class. And click Project Managed DLL->Properties->Configuration Properties->Common Language Runtime Support->Common Language Runtime Support (, \clr) in "Solution", and then compile to generate DLL.
There is the following code in clrClass.h:
#pragmaonce
public ref class clrClass
{
public:
clrClass(void);
~clrClass(void);
intmember; //self add
voidshowImage(); //Self-added
};
There is the following code in clrClass.cpp:
#include"clrClass.h"
#include"Functions.h"//Self-added
clrClass::clrClass(void)
{
}
clrClass::~clrClass(void)
{
}
voidclrClass::showImage() //Self-added
{
show();
}
4. C# calls the Dll file generated by C++
Create a new C# console program, add reference -> browse -> select the generated DLL to add.
