Method of storing a date

Question

I was wondering if there is a way to get a date without writing your own function. Something such as accessing the date set for the system. I tried

char dateStr[9];
_strdate(dateStr);

with the included time header, but I got compiler error ISO C++ forbids declaration of _strdate with no type. I thought _strdate was already declared and defined in the header so it wouldn't need a type definition. Could the problem be that I have those 2 lines inside of a struct? Are there any better way to store a date? Thanks.

#include "std_lib_facilities.h"

//Classes-----------------------------------------------------------------------

class Book{
public:
       Book(){}; // default constructor
       //operators
       friend ostream& operator<<(ostream& out, const Book& val);
       bool Book::operator==(const Book& check);
       //member functions
       string title();
       string author();
       string genre();
       int copyright();
       void ISBN();
       bool checkout();
private:
        string title_;
        string author_;
        string genre_;
        int copyright_;
        int ISBN1;
        int ISBN2;
        int ISBN3;
        char ISBN4;
        bool checkout_;
};

class Patron{
public:
       Patron(){}; //default constructor
       //member functions
       string name();
       int libnumber();
       double setfee();
private:
        string name_;
        int libnumber_;
        double libfees;
};

class Library{
public:
       vector<Book> books;
       vector<Patron> patrons;
       struct Transaction{
              Book book;
              Patron patron;};
       vector<Transaction> transactions;
};
// Error Function---------------------------------------------------------------

void _error(const string& s)
{
     cout << endl;
     cout << "Error: " << s << endl;
     cout << endl;
}

// Book Member Functions--------------------------------------------------------

string Book::title()
{
       cout << "Title: ";
       getline(cin,title_);
       cout << endl;
       return title_;
}

string Book::author()
{
       cout << "Author: ";
       getline(cin,author_);
       cout << endl;
       return author_;
}

string Book::genre()
{
       cout << "Genre(Fiction, Nonfiction, Periodical, Biography, Children): ";
       cin >> genre_;
       cout << endl;
       if((genre_!="Fiction")&&(genre_!="Nonfiction")&&(genre_!="Periodical")&&
          (genre_!="Biography")&&(genre_!="Children")) _error("Invalid genre.");
       else return genre_;
}

int Book::copyright()
{
    cout << "Copyright: ";
    cin >> copyright_;
    cout << endl;
    return copyright_;
}

void Book::ISBN()
{
     cout << "ISBN (4 entries. Use spaces): ";
     cin >> ISBN1 >> ISBN2 >> ISBN3 >> ISBN4;
     if((ISBN1<0) || (ISBN2<0) || (ISBN3<0) || (ISBN1>9) || (ISBN2>9) || (ISBN3)>9)
               _error("Must be single digit.");
     else if(!isdigit(ISBN4) && !isalpha(ISBN4))
               _error("Must be single digit or letter.");
     else{ cout << endl;
           return;}
}

bool Book::checkout()
{
     char check;
     cout << "Checked out?(Y or N): ";
     cin >> check;
     switch(check){
     case 'Y':
          cout << endl;
          return true;
          break;
     case 'N':
          cout << endl;
          return false;
          break;
     default: 
              _error("Must be Y or N.");}
}

// Patron Member Functions------------------------------------------------------

string Patron::name()
{
       cout << "Name: ";
       getline(cin,name_);
       cout << endl;
       return name_;
}

int Patron::libnumber()
{
    cout << "Libnumber: ";
    cin >> libnumber_;
    cout << endl;
    return libnumber_;
}

double Patron::setfee()
{
       cout << "Fee due: ";
       cin >> libfees;
       cout << endl;
       return libfees;
}

// Patron Helper Functions------------------------------------------------------

bool isfee()
{
     char isfee_;
     cout << "Does patron have fee due?(Y or N): ";
     cin >> isfee_;
     cout << endl;
     if((isfee_!='Y') && (isfee_!='N')) _error("Must use Y or N.");
     else return(isfee_=='Y');
}

// Operator Overloads-----------------------------------------------------------

ostream& operator<<(ostream& out, const Book& val){
         out << "Title: " << val.title_ << endl;
         out << "Author: " << val.author_ << endl;
         out << "ISBN: " << val.ISBN1 << "-" << val.ISBN2 << "-" << val.ISBN3 << "-" << val.ISBN4 << endl;
         out << endl;
         return out;}

bool Book::operator==(const Book& check){
     return((ISBN1 == check.ISBN1) && (ISBN2 == check.ISBN2) && (ISBN3 == check.ISBN3)
             && (ISBN4 == check.ISBN4));}

// Main Helpers-----------------------------------------------------------------

void runBook()
{
     Library bookstore;
     char notfinished;
     bool bookfinished = false;
     while(!bookfinished)
        {
          Book book;
          book.title();
          book.author();
          book.genre();
          book.copyright();
          book.ISBN();
          book.checkout();
          bookstore.books.push_back(book);
          cout << "Do you wish to store another book?(Y or N): ";
          cin >> notfinished;
          if(notfinished == 'Y'){ 
                         cin.ignore();
                         cout << endl;}
          else if(notfinished == 'N'){
                                       bookfinished = true;
                                       cout << endl;}
          else _error("Must be Y or N");
          }
}

void runPatron()
{
     Library patronstore;
     bool patronfinished = false;
     char notfinished;
     while(!patronfinished)
    {
      Patron patron;
      patron.name();
      patron.libnumber();
      if(isfee()){
                  patron.setfee();}
      cin.ignore();
      runBook(); // Call book function
      patronstore.patrons.push_back(patron);
      cout << "Is there another patron?(Y or N): ";
        cin >> notfinished;
        if(notfinished == 'Y'){ 
                         cin.ignore();
                         cout << endl;}
          else if(notfinished == 'N') patronfinished = true;
          else _error("Must be Y or N");
    }
}

// Main-------------------------------------------------------------------------   

int main()
{    
 runPatron();
     keep_window_open();
}

If you go to class Library and into the Transaction struct, that is where I want to store the date.

Answer 1

There is no such standard C++ function as strdate. Whether putting those lines "inside a struct" causes a problem is impossible to say without seing the code. I suggest what you really want is the asctime() function, or one of its relatives.

Answer 2

Where to start? Difficult to tell without seeing the code, but here's some thoughts.

First, you should probably NOT store the date as a character array within your struct because that will make manipulation of it awkward. Better to store it in it's native form as a time_t, and convert it to/from strings as required.

Second, if you must store it as ascii, don't store it as char[]. You're just asking for buffer overruns etc. Use string or vector

However, I think the real answer to your question concerns constructors. If you want Transaction to hold a date, then define it like this

struct Transaction
{
   char dateStr[9];
}

If you want transactions to be datestamped, then assign the date in the constructor

struct Transaction
{
   char dateStr[9];

   Transaction()
   {
      _strdate(dateStr); // or asctime or whatever
   }
}

Now, whenever you create a Transaction, it will automatically be filled with the return value from _strdate, whatever that is. Here's how I'd do it with time_t.

#include <stdio.h>
#include <time.h>

struct Transaction
{
  time_t theTime;

  Transaction()
  {
    theTime = time(NULL);
  }
}