有关ANSI C、ISO C、GNU C、POSIX C

参考：

https://segmentfault.com/a/1190000012461553

https://blog.csdn.net/weixin_44395686/article/details/104904172

https://blog.csdn.net/shenwansangz/article/details/48738199?utm_medium=distribute.pc_relevant.none-task-blog-2~default~baidujs_baidulandingword~default-0.pc_relevant_paycolumn_v3&spm=1001.2101.3001.4242.1&utm_relevant_index=3

https://blog.csdn.net/smstong/article/details/51614857?spm=1001.2101.3001.6650.1&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1.pc_relevant_paycolumn_v3&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1.pc_relevant_paycolumn_v3&utm_relevant_index=2