C#调用C++编写的DLL函数, 以及各种类型的参数传递 z

1. 如果函数只有传入参数,比如:

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1. //C++中的输出函数
2. int__declspec(dllexport) test(constint N)
3. {
4. return N+10;
5. }

对应的C#代码为:

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1. [DllImport("test.dll", EntryPoint = "#1")]
2. publicstaticexternint test(int m);
3. privatevoid button1_Click(object sender, EventArgs e)
4. {
5. textBox1.Text= test(10).ToString();
6. }

2. 如果函数有传出参数,比如:

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1. //C++
2. void__declspec(dllexport) test(constint N, int& Z)
3. {
4. Z=N+10;
5. }

对应的C#代码:

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1. [DllImport("test.dll", EntryPoint = "#1")]
2. publicstaticexterndouble test(int m, refint n);
3. privatevoid button1_Click(object sender, EventArgs e)
4. {
5. int N = 0;
6. test1(10, ref N);
7. textBox1.Text= N.ToString();
8. }

3. 带传入数组:

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1. void__declspec(dllexport) test(constint N, constint n[], int& Z)
2. {
3. for (int i=0; i<N; i++)
4. {
5. Z+=n[i];
6. }
7. }

C#代码:

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1. [DllImport("test.dll", EntryPoint = "#1")]
2. publicstaticexterndouble test(int N, int[] n, refint Z);
3. privatevoid button1_Click(object sender, EventArgs e)
4. {
5. int N = 0;
6. int[] n;
7. n = newint[10];
8. for (int i = 0; i < 10; i++)
9. {
10. n[i] = i;
11. }
12. test(n.Length, n, ref N);
13. textBox1.Text= N.ToString();
14. }

4. 带传出数组:

C++不能直接传出数组,只传出数组指针,

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1. void__declspec(dllexport) test(constint M, constint n[], int *N)
2. {
3. for (int i=0; i<M; i++)
4. {
5. N[i]=n[i]+10;
6. }
7. }

对应的C#代码:

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1. [DllImport("test.dll", EntryPoint = "#1")]
2. publicstaticexternvoid test(int N, int[] n, [MarshalAs(UnmanagedType.LPArray,SizeParamIndex=1)] int[] Z);
3. privatevoid button1_Click(object sender, EventArgs e)
4. {
5. int N = 1000;
6. int[] n, Z;
7. n = newint[N];Z = newint[N];
8. for (int i = 0; i < N; i++)
9. {
10. n[i] = i;
11. }
12. test(n.Length, n, Z);
13. for (int i=0; i<Z.Length; i++)
14. {
15. textBox1.AppendText(Z[i].ToString()+"n");
16. }
17. }

这里声明函数入口时,注意这句 [MarshalAs(UnmanagedType.LPArray,SizeParamIndex=1)] int[] Z

在C#中数组是直接使用的,而在C++中返回的是数组的指针,这句用来转化这两种不同的类型.

关于MarshalAs的参数用法以及数组的Marshaling,可以参见这篇转帖的文章: http://www.kycis.com/blog/read.php?21