记录下阅读的资料：
（总结待续）
1.https://blog.csdn.net/weixin_39640298/article/details/84503428
2.https://docs.microsoft.com/en-us/cpp/preprocessor/once?view=vs-2019
3.https://baike.baidu.com/item/%23pragma/706691
4.https://github.com/MicrosoftDocs/cpp-docs
5.