c# - 如何使用 P/INVOKE 将 C++ char* 编码为 C# 字符串

Question

我是 C++ 新手。我正在使用 PINVOKE 从 C# 调用 C++ 函数，并希望将字符串作为输出参数返回。但是我只得到一个空字符串。 int out 参数工作正常。

导入:

[DllImport ( @"UnamanagedAssembly.dll", CharSet = CharSet.Ansi)] 
public static extern int Activate(ref int numActivated,  StringBuilder eventsActivated);

extern "C" __declspec(dllexport) int Activate(int *p_NumActivated, char *p_EventsActivated) {return Activation::GetInstance()->Activate(p_NumActivated, p_EventsActivated);}

从 C# 调用我的 C++ 函数:

int numActivated = 0;
StringBuilder eventsActivated = new StringBuilder();
int status = Activate(ref numActivated, eventsActivated);  

C++函数:

int Activation::Activate(int *p_NumActivated, char *&p_EventsActivated)
{
    char *pTemp = "Hello";
    p_EventsActivated = pTemp;

    *p_NumActivated = 1;

    return 0;
}

Answer 1

StringBuilder eventsActivated = new StringBuilder(5);

代替

StringBuilder eventsActivated = new StringBuilder();