Homework Help - Create C++ Date class

**boygenuis** · 05-31-2014

I'm new to C++, in fact, this is my second week with it. I'm having issues with the header and cpp files during compilation. I'll add one or two errors now, then some later if I absolutely can't get them goin'. I appreciate your help, guys. Thank you.

Errors:
In file included from Date_Hardesty.cpp:14:0:
Date_Hardesty.h:22:13: error: ‘Date::Date(int, int, int)’ cannot be overloaded
Date_Hardesty.h:20:13: error: with ‘Date::Date(int, int, int)’
Date_Hardesty.cpp: In member function ‘void Date::setYear(int)’:
Date_Hardesty.cpp:53:4: error: ‘else’ without a previous ‘if’

This is my header file:

Code:

/*Line 11.*/ #include <string>
//Line 12. prevent multiple inclusions of header
/*Line 13.*/ #ifndef DATE_H
/* Line 14.*/ #define DATE_H

//Define Date class
class Date
{
public:
/*Line 20.*/   explicit Date (int = 1, int = 1, int = 2000);  /* my default constructor
                                                     sets date to Jan 1, 2000 */ 
   explicit Date (int month, int day, int year);  //my 3-arg constructor 
   void setMonth (int);      //function sets the Month
   void setDay (int);        //function sets the Day
   void setYear (int);       //function sets the Year
   int getMonth ();      //the function to return the int Month
   int getDay ();        //the function to return the int Day
   int getYear ();       //the function to return the int Year
   std::string getMonthName (int);  //to receive the string name of the  Month
   void print ();            //function to output Date as MM/DD/YYYY
   void printLong ();        //function to output Date as DD MonthName YYYY
   ~Date ();                //makin' sure everything gets destructed in order

private: 
   int month, day, year;
   
};  //end the class Date 

#endif

And, this is my Date_Hardesty.cpp file:

Code:

//Line 47. start function to set the Year according to the assignment's parameters
void Date::setYear (int y) 
{
   if (y < 1900)
      y = 1;
      year = y;
   else
      year = y; 
}  //end setYear

**jimblumberg** · 05-31-2014

You can't overload two functions with the same type and number of parameters.

Code:

/*Line 20.*/   explicit Date (int = 1, int = 1, int = 2000);  /* my default constructor
                                                     sets date to Jan 1, 2000 */
   explicit Date (int month, int day, int year);  //my 3-arg constructor

Really your "default" constructor should have no parameters and use an initialization list to assign the "default" values to the variables.

Code:

Date() : month(1), day(1), year(2000) {}

For the last error look at this snippet:

Code:

void Date::setYear (int y)
{
   if (y < 1900)
      y = 1;
      year = y;
   else

If you don't use braces in your if statements only one statement will be included in that if statement.

Jim

**boygenuis** · 05-31-2014

So, if I have this right, the if statement in my cpp file should look like:

Code:

void Date::setYear (int y)
{
   if (y < 1900)
   {
      y = 1;
      year = y;
   }
   else
      year = y; }  //end setYear

And, my Date class should look like:

Code:

#include <string>

//prevent multiple inclusions of header

#ifndef DATE_H

#define DATE_H

 

//Define Date class

class Date

{

public:
   Date () : month(1), day(1), year (200) {};           /* my default constructor

                                                           sets date to Jan 1, 2000 */  

   //explicit Date (int month, int day, int year);  //my 3-arg constructor 

   void setMonth (int);      //function sets the Month

   void setDay (int);        //function sets the Day
   void setYear (int);       //function sets the Year
   int getMonth ();      //the function to return the int Month
   int getDay ();        //the function to return the int Day
   int getYear ();       //the function to return the int Year
   std::string getMonthName (int);  //to receive the string name of the  Month
   void print ();            //function to output Date as MM/DD/YYYY
   void printLong ();        //function to output Date as DD MonthName YYYY
   ~Date ();                //makin' sure everything gets destructed in order
 
private: 
   int month, day, year;
    
};  //end the class Date 
 
#endif

**jimblumberg** · 05-31-2014

There is no reason you can't also have the three argument constructor as well. Or any of other unique constructors that may be required for the proper operation of your class.

Jim

**boygenuis** · 05-31-2014

A-ha. So this would also be cool?

Code:

public:
   explicit Date () : month(1), day(1), year (200) {};           /* my default constructor

                                                           sets date to Jan 1, 2000 */

   explicit Date (int month, int day, int year);  //my 3-arg constructor

This is great, thanks. I'll see if I can't figure the other errors out, then maybe ask more again.

**Elysia** · 06-01-2014

The ending brace for your code should go on a separate line. It helps code readability.
Your functions in your class definition should have parameter names; otherwise it is hard to know what arguments they take.
For example, if you say
explicit Date (int, int, int); //my 3-arg constructor
Then what parameters does it take? Presumably year, month and day, but in what order? If you follow the ISO standard, then it's Year, Month, Day. If you follow the reverse order, it's Day, Month, Year. If you follow the American standard, it may be Year, Day, Month.
Well, you see the problem. That's why you should always use descriptive names for parameters. See more at this linky.

**grumpy** · 06-01-2014

Originally Posted by boygenuis

A-ha. So this would also be cool?

Code:

public:
   explicit Date () : month(1), day(1), year (200) {};           /* my default constructor

                                                           sets date to Jan 1, 2000 */

   explicit Date (int month, int day, int year);  //my 3-arg constructor

It's permitted, yeah. It's coolness or otherwise depends on what you want to achieve. And whether you fix the typo or not

The first form you had (with three default values) can be invoked with zero, one, two, or three arguments. So with a single constructor of the form

Code:

    explicit Date (int = 1, int = 1, int = 2000);

can be invoked in any of the following forms;

Code:

    Date d0;                  //   equivalent to Date d0(1,1,2000)
    Date d1(5);             //    equivalent to Date d1(5,1,2000)
    Date d2(5,6);          //    equivalent to Date d2(5,6,2000)
    Date d3(5,6,1984);  //    equivalent to Date d2(5,6,1984)

All of the above call the same constructor.

With your two-constructors (one that accepts three arguments, one that accepts no arguments) you can only invoke the 0 argument and 3 argument forms. They are distinct constructors. The 1 and 2 argument forms are not permitted (unless you define them as well).

There is a trade-off that, with default argument values, the default arguments have to be specified in the class definition (or, more accurately, the declaration of the constructor within the class definition). If you need to change the default values for any reason, it is necessary to change the class definition (which will force the compiler to recompile every source file which uses your Date class). That can be a significant concern for large projects (for example, if you have a few hundred source files that #include <date.h>, all of them will be recompiled, whether they use the constructors or not).

With your second form (a non-argument constructor and a three-argument constructor) it is not necessary to place the default values in the class definition. If you separate the declaration from implementation of the constructor (e.g. declare the constructor in the header, implement it in date.cc) you can change the default values, without forcing a recompile.

Neither approach is more "cool" than the other .... the choice depends on what you are trying to achieve.

**boygenuis** · 06-02-2014

Thank you, all, for the help. Alas, I have two more errors which I've been unable to resolve.

Errors:
Date_Hardesty.cpp: In member function ‘std::string Date::getMonthName(int)’:
Date_Hardesty.cpp:81:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:83:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:85:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:87:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:89:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:91:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:93:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:95:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:97:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:99:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:101:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:103:7: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp:105:11: error: ‘name’ was not declared in this scope
Date_Hardesty.cpp: In member function ‘void Date:

rintLong()’:
Date_Hardesty.cpp:118:73: error: expected primary-expression before ‘int’
DateDemo.cpp: In function ‘int main()’:
DateDemo.cpp:38:37: error: expected primary-expression before ‘int’

That same ole header file:

Code:

#include <string>
//prevent multiple inclusions of header
#ifndef DATE_H
#define DATE_H

//Define Date class
class Date
{
public:
   explicit Date () : month (1), day (1), year (2000)  // my default
   {                                                   // constructor
                                                       // sets date to
   };                                                  // Jan 1, 2000
   explicit Date (int month, int day, int year);  //my 3-arg constructor 
   void setMonth (int);      //function sets the Month
   void setDay (int);        //function sets the Day
   void setYear (int);       //function sets the Year
   int getMonth ();          //the function to return the int Month
   int getDay ();            //the function to return the int Day
   int getYear ();           //the function to return the int Year
   std::string getMonthName (int);  //to receive the string name of the  Month
   void print ();            //function to output Date as MM/DD/YYYY
   void printLong ();        //function to output Date as DD MonthName YYYY
   ~Date ();                //makin' sure everything gets destructed in order

private: 
   int month, day, year;
   
};  //end the class Date 

#endif

excerpts from my Date_Hardesty.cpp file

Code:

//**LINE 77**  function to return the MonthName to main
std::string Date::getMonthName (int m)
{
   if (m = 1)
      name = "January";
   if (m = 2)
      name = "February";
   if (m = 3)
      name = "March";
   if (m = 4)
      name = "April";
   if (m = 5)
      name = "May";
   if (m = 6)
      name = "June";
   if (m = 7)
      name = "July";
   if (m = 8)
      name = "August";
   if (m = 9)
      name = "September";
   if (m = 10)
      name = "October";
   if (m = 11)
      name = "November";
   if (m = 12)
      name = "December";

   return name;  //send the Month's name back to main
} //end getMonthName

So, I tried adding a string "name" to the "private" area of my header, but that gave me the same errors. I tried adding "name" to my cpp file with my main function, but that also did not work. Clearly I should be initializing "name" somewhere else, but I don't know where.

Then, the errors about, "expected primary expression before 'int'" confuses me.

Code:

//**LINE 38** start function to set the Day according to the assignment's parameters
void Date::setDay(int d)  
{ 
   if (d >= 1 && d <= 31)
      day = d;
   else
      day = 1;
}  //end setDay

...
some more code
...

//**LINE 115** function to format the DD Month YYYY printLong function
void Date::printLong ()
{
    cout << setfill ('0') << setw (2) << getDay()  << " " << getMonthName(int) << " " << getYear()  << "\n";

}  //end printLong function

Your thoughts?

**jimblumberg** · 06-02-2014

Clearly I should be initializing "name" somewhere else, but I don't know where.

How about in the function where it is used, before you use it?

Code:

std::string Date::getMonthName (int m)
{
   std::string name = "Blank";
   ...

Also look at this snippet:

Code:

    cout << setfill ('0') << setw (2) << getDay()  << " " << getMonthName(int)

You need a variable name or a constant value in that last function call, not a type of variable.

Look at the following snippet:

Code:

void Date::setDay(int d) 
{
   if (d >= 1 && d <= 31)
      day = d;
   else
      day = 1;
}

What happens if the month happens to be Febuary? Or June, or any other month that has less than 31 days?

Jim

**Elysia** · 06-02-2014

>>Date_Hardesty.cpp:81:7: error: ‘name’ was not declared in this scope
Like it says, you have not declared a variable name in the current scope. Clearly, it's a local variable because its usefulness ends when the function ends, so declare it in your function.

>>Date_Hardesty.cpp:118:73: error: expected primary-expression before ‘int’
cout << setfill ('0') << setw (2) << getDay() << " " << getMonthName(int) << " " << getYear() << "\n";
What is that int supposed to do?

**boygenuis** · 06-02-2014

Declare it in the function itself!!! I should have seen that.

Thank you for catching the setDay error. I crossed it off my list, but the function wasn't finished. I'll revisit that tomorrow afternoon.

I'm still having issues with the
DateDemo.cpp: In function ‘int main()’:
DateDemo.cpp:38:37: error: expected primary-expression before ‘int’

Even though line 38 is commented. I are confoosed.

Code:

//**LINE 38** start function to set the Day according to the assignment's parameters
void Date::setDay (int d)  
{ 
   if (d >= 1 && d <= 31)
      day = d;
   else
      day = 1;
}  //end setDay

**Elkvis** · 06-03-2014

since you didn't post your main function, it's impossible for us to help you with that.

another thing that no one else seems to have commented on yet is the fact that getMonthName() will always return "December"

note that there is a difference between "=" and "=="

**boygenuis** · 06-03-2014

Sorry, got confused. Thanks for checking my comparisons in getMonthName

Here's my main function.

Code:

// DateDemo.cpp

#include <iostream>
#include <iomanip>
#include <string>
using std::cout;
using std::endl;
using std::setfill;
using std::setw;
using std::string;

#include "Date_Hardesty.h"

// note - you may need to change the definition of the main function to
// be consistent with what your C++ compiler expects.

//int _tmain(int argc, _TCHAR* argv[])
int main()
{
    Date d1;             // default ctor
    Date d2(7, 4, 1976); // July 4'th 1976
    Date d3(0, 15, 1880);// Adjusted by ctor to January 15'th 1900

    d1.print();         // prints 01/01/2000
    d1.printLong();     // prints 1 January 2000
    cout << endl;

    d2.print();         // prints 07/04/1976
    d2.printLong();     // prints 4 July 1976
    cout << endl;

    d3.print();         // prints 01/15/1900
    d3.printLong();     // prints 15 January 1900
    cout << endl;

    cout << "object d2's day is " << d2.getDay() << endl;
    cout << "object d2's month is "  << d2.getMonth() << 
    " which is " << d2.getMonthName(int) << endl;
    cout << "object d2's year is " << d2.getYear() << endl;

    return 0;
}

**jimblumberg** · 06-03-2014

Please re-read posts #9 and #10.

Jim

**boygenuis** · 06-03-2014

But if I declare a variable "name" or "month" or whatever in main, it won't contain whatever information from my Date_Hardesty.cpp or Date_Hardesty.h files. How would I get that variable in main to have this info?

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