C#调用c++dll的两种方法（静态方法和动态方法）
一.c#项目创建
1.创建一个console控制台程序。
2.把dll拷贝到c#生成的.exe程序的目录内。
3.在c#的program.cs类引入命名空间System.Runtime.InteropServices。
System.Runtime.InteropServices 命名空间提供了一系列类、接口和属性，主要用于促进托管代码（C# 代码）和非托管代码（如 C 或 C++ 代码）之间的互操作性。
它允许 C# 程序与 Windows API、动态链接库（DLL）、COM 组件等进行交互，使开发人员能够在 C# 程序中调用非托管代码，以及对 COM 组件进行操作。
二.调用c++ DLL方法一（静态调用）
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp3
{
class Program
{
[DllImport("Testdll.dll", CallingConvention = CallingConvention.Cdecl)]
extern static int add(int a, int b);
[DllImport("Testdll.dll", CallingConvention = CallingConvention.Cdecl)]
extern static int minus(int a, int b);
[DllImport("Testdll.dll", CallingConvention = CallingConvention.Cdecl)]
extern static IntPtr Getversion();
static void Main(string[] args)
{
Console.WriteLine(add(1,6));
Console.WriteLine(minus(1, 6));
IntPtr pStr = Getversion();
string version = Marshal.PtrToStringAnsi(pStr);
Console.WriteLine(version);
Console.ReadKey();
}
}
}
三.调用c++ DLL方法二（动态调用）
这样做的好处是，dll不用放到exe的根目录，可以自己放到任何地方，方便管理。
1.新建一个DLLWrapper类。
代码如下：
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp3
{
public class DLLWrapper
{
[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr LoadLibrary(string lpFileName);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool FreeLibrary(IntPtr hModule);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool SetDllDirectory(string lpPathName);
IntPtr pDll = IntPtr.Zero;
public bool LoadDynamicLibrary(string path,string dlname)
{
if (File.Exists(Path.Combine(path, dlname)))
{
SetDllDirectory(path);
pDll = LoadLibrary(dlname);
if (pDll == IntPtr.Zero)
{
Console.WriteLine("Failed to load DLL");
return false;
}
else
{
Console.WriteLine("load DLL success");
return true;
}
}
else
{
Console.WriteLine("DLL is not exist");
return false;
}
}
public bool FreeDllIntPtr()
{
bool resultFree = FreeLibrary(pDll);
if (resultFree)
{
Console.WriteLine("DLL successfully unloaded.");
return true;
}
else
{
Console.WriteLine("Failed to unload DLL.");
return false;
}
}
}
}
2.在program.cs调用这个类
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp3
{
class Program
{
[DllImport("Testdll.dll", CallingConvention = CallingConvention.Cdecl)]
extern static int add(int a, int b);
[DllImport("Testdll.dll", CallingConvention = CallingConvention.Cdecl)]
extern static int minus(int a, int b);
[DllImport("Testdll.dll", CallingConvention = CallingConvention.Cdecl)]
extern static IntPtr Getversion();
static void Main(string[] args)
{
DLLWrapper Wrapper = new DLLWrapper();
//加载dll，传入dll的文件夹路径
Wrapper.LoadDynamicLibrary(Environment.CurrentDirectory+ "\\Library", "Testdll.dll");
Console.WriteLine(add(1,5));
Console.WriteLine(minus(1, 5));
IntPtr pStr = Getversion();
string version = Marshal.PtrToStringAnsi(pStr);
Console.WriteLine(version);
//释放dll
Wrapper.FreeDllIntPtr();
Console.ReadKey();
}
}
}