sscanf()和正则表达式 https://blog.csdn.net/kenby/article/details/4051018
strtok http://www.cnblogs.com/aduck/articles/2245364.html
C语言itoa()函数和atoi()函数详解(整数转字符C实现) https://www.cnblogs.com/bluestorm/p/3168719.html
c++面向对象编程填空 http://cxsjsxmooc.openjudge.cn/2018t3sprintallc/005/
答案 https://www.icourse163.org/learn/PKU-1002029030?tid=1002785058#/learn/content?type=detail&id=1003870383&cid=1004682685
