zcav.cpp: 在函数‘int main(int, char**)’中:
zcav.cpp:73:33: 错误:‘strdup’在此作用域中尚未声明
userName = strdup(optarg);
^
zcav.cpp:112:27: 错误:‘strcmp’
解决办法:在zcav.cpp中加入
#include<string.h>
https://stackoverflow.com/questions/40766055/error-strdup-was-not-declared-in-this-scope