c#中引用c++动态库

        [System.Runtime.InteropServices.DllImportAttribute("visual_pick.dll", SetLastError = true)]
        public static extern int start();


        [System.Runtime.InteropServices.DllImportAttribute("visual_pick.dll", SetLastError = true)]
        public static extern int stop();


        [System.Runtime.InteropServices.DllImportAttribute("visual_pick.dll", SetLastError = true)]
        public static extern IntPtr getInfo();


        [System.Runtime.InteropServices.DllImportAttribute("visual_pick.dll", SetLastError = true)]
        public static extern int getInfoSize();

调用名字需要跟c++中函数名一致，结构体类型使用指针接收(IntPtr)，对应调用代码和实体定义如下：

public void GetObjectInfo()
        {
                try
                {
                    //获取结构体字节大小
                    var size = Marshal.SizeOf(typeof(pickObjectInfoType));
                    //获取个数
                    var pickSize = getInfoSize();

                    if (pickSize > 0)
                    {
                        //获取对应方法内存地址，调用方法获取对应方法得到数组内存地址
                        var infosIntptr = getInfo();
                        for (int inkIndex = 0; inkIndex < pickSize; inkIndex++)
                        {
                            //根据获取内存地址进行数据偏移计算，得到对应指针指向的内存地址
                            IntPtr ptr = (IntPtr)(infosIntptr.ToInt64() + (inkIndex * size));
                            //根据内存地址转换结构体获取数据
                            pickList.Add((pickObjectInfoType)Marshal.PtrToStructure(ptr, typeof(pickObjectInfoType)));
                            Marshal.FreeHGlobal(ptr);
                        }

                    }
                }
                catch (Exception ex)
                {
                throw new Exception(ex.Message);
                }
        }

[StructLayout(LayoutKind.Sequential)]
    public struct pickObjectInfoType
    {
        public float x; 
        public float y; 
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 40)]//对应c++类型字节数，c++需要用char* 数组定义此类型
        public string z; 
    }