C++primer第5版课后练习习题答案9.51

#include <iostream>#include <vector>using namespace std;unsigned getmonth(const string & smonth);class cdate{public :friend void print_cdate(cdate & cd){cout<<cd.year<<"年"<<cd.month<<"月"<<cd.day<<"日"<<endl;}cdate()=default;cdate (string & sday);private:unsigned year;unsigned month;unsigned day;};cdate::cdate (string & sday){year=stoi(sday.substr(sday.size()-4,4));string::size_type pos=0;pos=sday.find_first_of(" /");month=getmonth(sday.substr(0,pos));pos++;day=stoi(sday.substr(pos,sday.find_first_not_of("0123456789",pos)-pos));}unsigned getmonth(const string & smonth){vector<string> vmonth = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};vector<string> vnmonth={"1","2","3","4","5","6","7","8","9","10","11","12"};//vector<string> vsmonth={"Jan","Fer","Mar","Apr","May","Jun","Jul","Aug","Sept","Oct","Nov","Dec"};for (decltype(vmonth.size()) i = 0; i != 12; ++i){if (vmonth[i].compare(0, 3, smonth) == 0 || vmonth[i].compare(smonth) == 0||vnmonth[i].compare(smonth)==0){return i + 1;}}return 0;}int main(){string str1 = "1/2/1990", str2 = "Apr 3 1989", str3 = "October 4, 1980";cdate mydate(str1);print_cdate(mydate);cdate mydate2(str2);print_cdate(mydate2);cdate mydate3(str3);print_cdate(mydate3);return 0;}