c# - 从 C++ DLL 获取 char * 到 C# 应用程序

Question

我在 C++ DLL 中导出了函数:

extern "C" int _stdcall info(int aError, char * description, int *aLen)

尝试从 C# 应用程序调用它。

声明:

[DllImport("mydll.dll", CallingConvention = CallingConvention.StdCall)] public static extern int info(int aError,   StringBuilder description, ref int length);

调用:

StringBuilder buffer = new StringBuilder();
fr = info(5, buffer, ref 256);

从第一个角度来看，这似乎可行。但它真的安全吗？我的意思是 StringBuilder 是否会始终管理来自 info 到 buffer 变量的字符串的足够内存？

我在声明中写了StringBuilder description，我应该添加ref吗？

Answer 1

I mean will StringBuilder always manage enough memory for string that comes from info to buffer variable?

您应该始终使用获取容量的构造函数来指定 StringBuilder 的初始容量:

int size = 256;
StringBuilder buffer = new StringBuilder(256);
fr = info(5, buffer, ref size);