Code Analysis： friend： C++中友元（友元函数和友元类）的用法和功能_friend class a<b>-CSDN博客 [C++：不如Coding]（11）：友元函数与友元类_哔哩哔哩_bilibili Here is a simple explanation: By using the mechanism of classes, data hiding and e

Preface: I just want 放洋屁，and then learn graphics. So,This essay is born. I will show you the whole process of my study,Including the bugs I created. Cool lets begin! Download: BaiduNetworkDisk:fr