C# 调用 Qt Dll 返回 int 和const char *

写了两个函数接口, 一个返回int, 另一个返回const char *字符串

dll方法返回const char * 时, c# 程序使用IntPtr类型声明, 不然会乱码

Qt dll 接口函数定义:

main.cpp

extern "C" __declspec(dllexport) int add(int numberA, int numberB)
{
    return numberA + numberB;
}

extern "C" _declspec(dllexport) const char *sayHi()
{
    //这里可以定义中文
	const char * s = "Hi";
	return s;
}

C#调用

    [DllImport("qtdialog.dll", EntryPoint = "add",  CallingConvention = CallingConvention.Cdecl)]
    public static extern int add(int numberA, int numberB);

    [DllImport("dll.dll", EntryPoint = "sayHi", CallingConvention = CallingConvention.Cdecl)]
    public static extern IntPtr sayHi();

    private void buttonAdd_Click(object sender, RoutedEventArgs e)
        {
            int getAddValue = add(1, 2);

            // 接收到的字符串需要转成ASCII
            IntPtr temp = sayHi();
            string str = Marshal.PtrToStringAnsi(temp).Trim();
        }