C#调用c++ dll 方式

1. 对象不可当参数，容易出现指针无法解析

比如string， 需要在导出为char *

#ifdef GRIDXY2LONLAT_EXPORTS
#define GRIDXY2LONLAT_API __declspec(dllexport)
#else
#define GRIDXY2LONLAT_API __declspec(dllimport)
#endif

 extern "C"   XXX_API int funca(char * AFileName);

 

  .CPP

   int funca(char* AFileName)
 {
    return classbb::GetInstance().funca(AFileName);
 }

2 代码示例：

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
using System.Runtime;

namespace WindowsFormsApplication
{
    public partial class Form1 : Form
    {
        [DllImport(@"XXXXX.dll", EntryPoint = "funca", CharSet = CharSet.None, CallingConvention = CallingConvention.Cdecl)]
        public static extern int  <span style="font-family: Arial, Helvetica, sans-serif;">funca </span><span style="font-family: Arial, Helvetica, sans-serif;">( string pFileName);</span>

        [DllImport(@"<span style="font-family: Arial, Helvetica, sans-serif;">XXXXX</span><span style="font-family: Arial, Helvetica, sans-serif;">.dll", EntryPoint = "</span><span style="font-family: Arial, Helvetica, sans-serif;">XXXXX</span><span style="font-family: Arial, Helvetica, sans-serif;">", CharSet = CharSet.None, CallingConvention = CallingConvention.Cdecl)]</span>
        public static extern int FUNB(  double ALon,   double ALat,ref int  Aearthid,ref int  Axoffset,ref int Ayoffset,int GridSize);

  

        public Form1()
        {
            InitializeComponent();
        }

        string convert_xy_by_gridsize(int EarthID, double X, double Y, int gridSize)
        {

            return "'" + EarthID + "," + (int)(X >= 0 ? Math.Ceiling(X / gridSize) : Math.Floor(X / gridSize)) + "," +
            (int)(Y >= 0 ? Math.Ceiling(Y / gridSize) : Math.Floor(Y / gridSize)) + "'";

        }


        private void button1_Click(object sender, EventArgs e)
        {


            int iResult = FUNA(" InitValue.csv");

            double ALon = 103.71755642;
            double ALat = 29.56135396;

            //103.71755642,29.56135396
            int Aearthid = 0; int Axoffset = 0; int Ayoffset = 0;
            FUNCB(ALon, ALat, ref Aearthid, ref Axoffset, ref Ayoffset, 1);

            int i = 0;
            i++;
    

        }
    }
}