如何从C#传递和接收数据到非托管C++ DLL

Question

• 我没有完全访问DLL源,只有标题.
• 我实际代码中的参数名称更具描述性

嘿伙计们,我正在尝试调用一个非托管DLL,它接受所有char*变量,其中两个充当"返回"值.in1-8是输入,in9和10是长度为512的char*,并且是空的.调用完成后,应填充结果数据.

这是我正在尝试使用的示例定义:

[DllImport("mydll.dll")]
public static extern IntPtr foo(
    IntPtr in1,
    IntPtr in2,
    IntPtr in3,
    IntPtr in4,
    IntPtr in5,
    IntPtr in6,
    IntPtr in7,
    IntPtr in8,
    ref IntPtr result1,
    ref IntPtr result2);

这是我的电话:

IntPtr param1 = Marshal.StringToHGlobalUni("testdata");
IntPtr param2 = Marshal.StringToHGlobalUni("testdata");
IntPtr param3 = Marshal.StringToHGlobalUni("testdata");
IntPtr param4 = Marshal.StringToHGlobalUni("testdata");
IntPtr param5 = Marshal.StringToHGlobalUni("testdata");
IntPtr param6 = Marshal.StringToHGlobalUni("testdata");
IntPtr param7 = Marshal.StringToHGlobalUni("testdata");
IntPtr param8 = Marshal.StringToHGlobalUni("testdata");
IntPtr param9 = IntPtr.Zero;
IntPtr param10 = IntPtr.Zero;

foo(param1, param2, param3, param4, param5, param6, param7, param8, ref param9, ref param10);

要打印IntPtr,我正在做:

string str = Marshal.PtrToStringUni(param9);
Console.WriteLine(str);

在给我的"示例"中,C++调用如下所示:

char result1[512]="";
char result2[512]="";
foo("testdata", "testdata", "testdata", "testdata", "testdata", "testdata", "testdata", "testdata", result1, result2);
printf("%s,%s\n",result1,result2);

问题:我尝试的各种方式,包括char [512]转换为byte [],StringBuilder大小512,IntPtr等.每次返回时param9和param10值为空.任何人都可以帮我解决这个问题吗？提前致谢.

编辑 在下面的一些有用的评论和更多的谷歌搜索后,我修补我的凌乱的代码工作.这是编辑:

[DllImport("mydll.dll")]
public static extern IntPtr foo(
    IntPtr in1,
    IntPtr in2,
    IntPtr in3,
    IntPtr in4,
    IntPtr in5,
    IntPtr in6,
    IntPtr in7,
    IntPtr in8,
    IntPtr result1,
    IntPtr result2);

我摆脱了两个结果char数组的引用.

IntPtr param1 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param2 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param3 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param4 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param5 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param6 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param7 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param8 = Marshal.StringToHGlobalAnsi("testdata");
IntPtr param9 = Marshal.AllocHGlobal(512 * sizeof(int));
IntPtr param10 = Marshal.AllocHGlobal(512 * sizeof(int));

foo(param1, param2, param3, param4, param5, param6, param7, param8, param9, param10);

上面我分配了param9和10而不是IntPtr.Zero

//printing..
string str = Marshal.PtrToStringAnsi(param9);

使用字符串也是一种更简单的方法,感谢下面的答案:

[DllImport("mydll.dll")]
public static extern IntPtr foo(
    string in1,
    string in2,
    string in3,
    string in4,
    string in5,
    string in6,
    string in7,
    string in8,
    StringBuilder result1,
    StringBuilder result2);

然后:

StringBuilder resultA = new StringBuilder(512);
StringBuilder resultB = new StringBuilder(512);

foo("test", "test", "test", "test", "test", "test", "test", "test", resultA, resultB);

打印:

Console.WriteLine(resultA.ToString());

它看起来好多了,现在实际上有效,谢谢你们!很容易混淆50个谷歌搜索标签打开.

Answer 1

假设您有以下c声明

extern "C" __declspec(dllexport) {
    void foo(char * input, char * output);
}

我将定义以下C#定义:

[DllImport("mydll.dll", EntryPoint="foo")]
public static extern void Foo(string input, StringBuilder output);

并且呼叫将是这样的:

string input = "input";
var output = new StringBuilder(512);
Foo(input, output);

如果可能,尽量避免使用不安全的代码.