Validation in classes

[QueenJJ]

I have the following class but can't seem to figure out how to validate the inputs.
//Define Default Constructor
DateC::DateC()
{
day = 1;
month = 1;
year = 2000;
}
//Define Constructor
DateC::DateC(int d, int m, int y)
{
day = d;
month = m;
year = y;
}
//Define GetDay
int DateC:: getday()
{
return day;
}
//Define GetMonth
int DateC:: getmonth()
{
return month;
}
//Define GetYear
int DateC:: getyear()
{
return year;
}

[doug4]

I fleshed out your code and showed you one way to validate the month field. You can reuse the validateMonth function if you add a setMonth() function to your class. What you do with the field when validation fails is totally up to you.

#include <iostream>

class DateC
{
public:
    DateC();
    DateC(int d, int m, int y);
    int getday();
    int getmonth();
    int getyear();
private:
    int day;
    int month;
    int year;

    bool validateMonth(int monthToValidate);
};

//Define Default Constructor
DateC::DateC()
{
    day = 1;
    month = 1;
    year = 2000;
};

//Define Constructor
DateC::DateC(int d, int m, int y)
{
    day = d;

    if (validateMonth(m))
    {
        month = m;
    }
    else
    {
        month = 1;
    }
    year = y;
}

//Define GetDay
int DateC:: getday()
{
    return day;
}
//Define GetMonth
int DateC:: getmonth()
{
    return month;
}
//Define GetYear
int DateC:: getyear()
{
    return year;
}

bool DateC::validateMonth(int monthToValidate)
{
    return ((monthToValidate > 0) && (monthToValidate <= 12));
}

int main()
{
    DateC d1;
    std::cout << d1.getday() << "/" << d1.getmonth() << "/" << d1.getyear() << std::endl;

    DateC d2(11, 3, 2020);
    std::cout << d2.getday() << "/" << d2.getmonth() << "/" << d2.getyear() << std::endl;

    DateC d3(11, 15, 2020); // Illegal month value
    std::cout << d3.getday() << "/" << d3.getmonth() << "/" << d3.getyear() << std::endl;

    return 0;
}

[jonnin]

this is the kind of thing you are going to do a lot of, and you may want some sort of tool you can use to validate common things (ints and doubles within ranges for examples). I keep mine as stand alone function / procedural design but you can bundle into an object if you feel a need. Putting them into the class, though, limits re-use, so consider moving it out.

[dhayden]

doug4's validateMonth() is a good start, but you'll need more. I suggest a general validate() method that validates the entire date. After all, some days are only valid on some months, or some months in some years (think February 29).