scanf 与 scanf_s

https://blog.csdn.net/Gnewocean/article/details/83793744

https://blog.csdn.net/ricky_lyq/article/details/77863527

https://blog.csdn.net/louyijie/article/details/53364447

scanf的结束标志是空格和回车键，而gets的结束标志为回车键，输入字符串时，一般采用gets；