利用已有库对excel进行读和写
读excel的内容:libxls库
C: https://github.com/evanmiller/libxls 或 http://libxls.sourceforge.net/
参考博客:https://www.cnblogs.com/sancong/p/6439614.html
C++: https://github.com/tidyverse/readxl
往excel写内容:libexcel库
C:https://github.com/devinsmith/libexcel