<iomanip>传送门：https://baike.baidu.com/item/iomanip/3319954?fr=aladdin
linux为何用./运行程序：https://blog.csdn.net/lijinshanba/article/details/81985961
snprintf使用：https://baike.baidu.com/item/snprintf%28%29/708910?fromtitle=snprintf&fromid=7320492&fr=aladdin