anxious! Wait online. Questions about calling unmanaged .exe programs in C #?

frank_jojo

The .exe program of an application developed in C ++ (currently also being developed in vs) is referenced in the C # environment using DllImport, and there appears "trying to read or write protected memory. This usually indicates that other memory is corrupted. "error. I hope you masters to solve it.
C ++:
EXTERN_C int _declspec (dllexport) GetInt ()
{
Ranch
CFile f ("C:\\t.txt", CFile :: modeReadWrite); // If you add this sentence, an error will occur. If you log out, the program can be executed smoothly and the file path is fine.

return 222;
}

c #:
[DllImport ("DrawSystem1.exe", EntryPoint = "_GetInt @ 0", CharSet = CharSet.Auto)]
        public static extern int GetInt ();

Thank you all masters, this issue must be resolved today. It's been several days, if it can't be resolved, it will delay the process.

苹果小刀

Does the current user have permission to t.txt?

psycholmu

Check if the file's attributes are correct

frank_jojo

The problem seems not to be in the file.
I use the following to test it is not easy to use.
EXTERN_C int _declspec (dllexport) GetInt ()
{
The
// CFile f ("C:\\t.txt", CFile :: modeReadWrite);
MessageBox (0, "TTTTT", "CCCCC", 0);

return 222;
}

Please also help to analyze

电车男

Why use the method in EXE? Is it bad to use DLL?

frank_jojo

Yes, but the effect is the same!
I was also new to this thing, depressed. Also hope that you masters help!

瞌睡的鱼鱼

Try to change the c ++ function calling method to stdcall (guess)

freegreat

I have the same problem, my C ++ dll header file is as follows:
namespace MathFuncs
{
    class MyMathFuncs
    {
    public:
        // Returns a + b
        static __declspec (dllexport) double Add (double a, double b);
        
// Returns a-b
        static __declspec (dllexport) double Subtract (double a, double b);

        // Returns a * b
        static __declspec (dllexport) double Multiply (double a, double b);

        // Returns a / b
        // Throws DivideByZeroException if b is 0
        static __declspec (dllexport) double Divide (double a, double b);
    };
}
Then it can be called in C ++, but encountered problems in C #.
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace MyCSharpExecRefsDll
{
    class Program
    {
        static void Main (string [] args)
        {
            myWin32 mywin32 = new myWin32 ();
            Console.WriteLine (myWin32.Add (3, 4));

        }
            public class myWin32
        {
            [DllImport ("MathFuncsDll1.dll")]
            public static extern double Add (double a, double b);
            [DllImport ("MathFuncsDll1.dll")]
            public static extern double Subtract (double a, double b);
            [DllImport ("MathFuncsDll1.dll")]
            public static extern double Multiply (double a, double b);
            [DllImport ("MathFuncsDll1.dll")]
            public static extern double Divide (double a, double b);

        }

    }
}
When calling, always say there is no such entry.
Unable to find entry point named "Add" in DLL "MathFuncDll1.dll"

frank_jojo

If you write it like this, you can't find the entry point of the program.
EXTERN_C void __stdcall GetInt ()
{
The
// CFile f ("C:\\t.txt", CFile :: modeReadWrite);
MessageBox (0, "TTTTT", "CCCCC", 0);

// return 222;
}

frank_jojo

TO:freegreat
You write the method outside the class, it should be fine. Then you use depends to open the dll file you edited, in which you can view the entry function name.