c++ primer 5 th p328 9.5.5节 练习9.51 自己编写的答案_c++primer9.51

#include <iostream>
#include <string>
#include <vector>
using namespace std;
unsigned long  find_year_of_type1(const string &);
int which_type(const string &);
class DATE{
public:
  static  vector<string> all_month;
  static   vector<string> all_abbr_month;
  DATE() = default;
  DATE(const string & date_input)
    {
    
      //There is three types of date.
      //type1:January 1,1900 
      //type2:1/1/1990
      //type3:Jan 1 1900
    int type_id;
    type_id = which_type(date_input);
 
     // find month
    string::size_type  pos,day_year_pos;
    int label = 0;
    if(type_id == 1)
      { int month_order = 1;   
        for(vector<string>::iterator i = DATE::all_month.begin() ; i != DATE::all_month.end(); ++ i)
 	  {
             pos =  date_input.find(*i);
	     if(pos != string::npos)
	       {
                 //month = *i;
		 label = 1;
		 month = month_order;
	       }//if
	     ++ month_order;
	  }//for
	if(label == 0)
	  cout << "error month!!!" << endl;
	// find the day and year
	
	day = stoi(date_input.substr(date_input.find_first_of("0123456789")));
	if(day >31 || day < 0 )
	  cout << "error day!!!" << endl;
 
	year = find_year_of_type1(date_input);
	if(year < 0)
	  cout << "wrong year!!!" << endl;
	
      }//if(type_id == 1)
    else if(type_id == 2)
      {
	month = stoul(date_input);
	size_t day_beginning_position = 0;
        size_t day_ending_position = 0;
	size_t first_bar_position = date_input.find_first_of('/');
	size_t second_bar_position = date_input.find_last_of('/');
	day = stoul(date_input.substr(first_bar_position + 1));
        year = stoul(date_input.substr(second_bar_position + 1)); 
 
     
      }  
    //type3:
    else {
      size_t first_backspace_position = date_input.find_first_of(' ');             
      size_t second_backspace_position = date_input.find_last_of(' ');
       for(size_t i = 0; i != DATE::all_abbr_month.size() ; ++i)
	{
	  if((date_input.find(all_abbr_month[i])) != string::npos)
	    {
              month = i + 1;
	      break;
	    }
	}
       
     
       day = stoul(date_input.substr(date_input.find_first_of("0123456789")));
    if(day  > 31 || day < 0)
      {
        cout << "error day!!!" << endl;
      }
    year = stoul(date_input.substr(second_backspace_position + 1));
    if(year < 0)
      cout << "error year!!!" << endl;
    }//type3
    }//DATE
  ostream & display_date(ostream &os)
  {
    os << year << " " << month << " " << day; 
    return os;
  }
private:
  unsigned year = 0;
  unsigned month = 0;
  unsigned day = 0;
};
 
vector<string> DATE::all_month{"January","February","March","April","May","June","July","August","September","October","November","December"};
vector<string> DATE::all_abbr_month{"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};
int sum_int(vector<string> &);
int main()
{
  string s = "January 1,1900";
  string s1 = "1/1/1990";
  string s2 = "Jan 1 1900";
  cout << which_type(s) << endl;
  cout << which_type(s1) << endl;
  cout << which_type(s2) << endl;
 
  DATE d1("January 23,2005");
  d1.display_date(cout) << endl;
  DATE d2("2/27/2020");
  d2.display_date(cout) << endl;
  DATE d3("Feb 3 2020");
  d3.display_date(cout) << endl;
 
  
  return 0;
}
 
int which_type(const string &s)
{ //test if date of "s" type1:
  for(int i = 0 ;i != s.size(); ++ i)
    {
      if(s[i] == ',')
	return 1;
      if(s[i] == '/')
	return 2;
    }
  return 3;
}  
 
unsigned long find_year_of_type1(const string& date_input)
{
  unsigned number_beginning_position = 0;
  unsigned past_number_ending_position = 0;//after the last number position
  size_t i = 0;
  for(;i != date_input.size() ; ++ i)
    {
      if(date_input[i] == ',')
	{
	  number_beginning_position = i+1;
	  break;
	}
    }
unsigned long calculated_year = stoul(date_input.substr(number_beginning_position));  
    return calculated_year;
}
  

r@r:~/computer_language/c++/9/9.5.5/ex$ ./123
1
2
3
2005 1 23
2020 2 27
2020 2 3
 
 
说明：前三个运行结果 1 2 3 是测试一个函数而已。