C#調用C++編寫的DLL函數, 以及各類類型的參數傳遞 （轉載）

 

 

C#調用C++編寫的DLL函數, 以及各類類型的參數傳遞  

1. 若是函數只有傳入參數,好比:

C/C++ Code Copy Code To Clipboard

//C++中的輸出函數
int __declspec(dllexport) test(const int N)
{
return N+10;
}

對應的C#代碼爲:

C# Code Copy Code To Clipboard

[DllImport("test.dll", EntryPoint = "#1")]
public static extern int test(int m);

private void button1_Click(object sender, EventArgs e)
{
textBox1.Text= test(10).ToString();
}

2. 若是函數有傳出參數,好比:

C/C++ Code Copy Code To Clipboard

//C++
void __declspec(dllexport) test(const int N, int& Z)
{
Z=N+10;
}

對應的C#代碼:

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[DllImport("test.dll", EntryPoint = "#1")]
public static extern double test(int m, ref int n);

private void button1_Click(object sender, EventArgs e)
{
int N = 0;
test1(10, ref N);
textBox1.Text= N.ToString();
}

3. 帶傳入數組:

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void __declspec(dllexport) test(const int N, const int n[], int& Z)
{
for (int i=0; i<N; i++)
{
Z+=n[i];
}
}

C#代碼:

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[DllImport("test.dll", EntryPoint = "#1")]
public static extern double test(int N, int[] n, ref int Z);

private void button1_Click(object sender, EventArgs e)
{
int N = 0;
int[] n;
n = new int[10];
for (int i = 0; i < 10; i++)
{
n[i] = i;
}
test(n.Length, n, ref N);
textBox1.Text= N.ToString();
}

4. 帶傳出數組:

C++不能直接傳出數組,只傳出數組指針,

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void __declspec(dllexport) test(const int M, const int n[], int *N)
{
for (int i=0; i<M; i++)
{
N[i]=n[i]+10;
}
}

對應的C#代碼:

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[DllImport("test.dll", EntryPoint = "#1")]
public static extern void test(int N, int[] n, [MarshalAs(UnmanagedType.LPArray,SizeParamIndex=1)] int[] Z);

private void button1_Click(object sender, EventArgs e)
{
int N = 1000;
int[] n, Z;
n = new int[N];Z = new int[N];
for (int i = 0; i < N; i++)
{
n[i] = i;
}
test(n.Length, n, Z);
for (int i=0; i<Z.Length; i++)
{
textBox1.AppendText(Z[i].ToString()+"n");
}
}

這裏聲明函數入口時,注意這句 [MarshalAs(UnmanagedType.LPArray,SizeParamIndex=1)] int[] Z

在C#中數組是直接使用的,而在C++中返回的是數組的指針,這句用來轉化這兩種不一樣的類型.

關於MarshalAs的參數用法以及數組的Marshaling,能夠參見這篇轉帖的文章: http://www.kycis.com/blog/read.php?21

5. 傳出字符數組：

C++定義：

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void __declspec(dllexport) test(int i, double &a, double &b, char t[5])

C#對應聲明：

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[DllImport("dll.dll", EntryPoint = "test")]
public static extern void test(int i, ref double a, ref double b, [Out, MarshalAs(UnmanagedType.LPArray)] char[] t);
。。。
            char[] t = new char[5];
            test(i, ref a, ref b, t);

字符數組的傳遞基本與4類似，只是mashalAs 時前面加上Out。