Calendar

#include <iostream>
#include <iomanip>
#include <string>
#include <stdio.h>
#include "date.h"
using namespace std;

Date::Date(int m, int d, int y)
{
    //century used for if the year ends on a number divisble by 1000
    int century;
    bool error = false;
    //needed for leap year
    if (y % 1000 == 0)
    {
        century = y;
    }
    //Month error check
    if (m < 1 || m > 12)
    {
        error = true;
    }
    //Year error check
    if (y < 1900)
    {
        error = true;
    }
    //Day less than 0 Check
    if (d <= 0)
    {
        error = true;
    }

    //Error check for correct day for each month
    switch (m)
    {
        //if february calculate if its a leap year and allow 29 if not do not allow 29
        case 2:
            if (d > 28)
            {
                error = true;
            }
            if (d == 29 && (y % 4 == 0 || century % 400 == 0))
            {
                d = 29;
            }
            break;
        //cascade effect for months that end in 30
        case 4:
        case 6:
        case 11:
            if (d > 30)
            {
                error = true;
            }
            break;
        //cascade effect for months that end in 31
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            if (d > 31)
            {
                error = true;
            }
            break;
    }
    //Assigning values to Private class
    //if the error is false than the values put into the constructor are
    //the private member functions
    if (error == false)
    {
        day = d;
        month = m;
        year = y;
    }
    //if the error is true than change the values to the defualt values
    else
    {
        day = 1;
        month = 1;
        year = 2019;
    }
}

//allows the user to input a date and see if its legal or not
void Date::input()
{
    //numbers are initalized so that if they don't enter it right it wont change and will results
    //in an error

    int m1 = -1, d2 = -1, y3 = -1, temp, temp2;
    string m, d, y;
    string date;
    bool illegal = false;
    //while loop so if you enter a bad value it prompt so enter again
    do
    {
        cout << "input date in month/day/year format: ";
        cin >> date;

        //if else blocks used for all the scenarios of two digit and one digit dates
        if (date[1] == '/')
        {
            m1 = '0' - date[0];
            m1 *= -1;
        }
        else
        {
            m = date[0] + date[1];
            temp = '0' - date[1];
            temp2 = '0' - date[0];
            m1 = temp2 * 10 + temp;
            m1 *= -1;
        }
        if (date[1] == '/' && date[3] == '/')
        {
            d2 = ('0' - date[2]) * -1;
        }
        else if (date[1] == '/' && date[4] == '/')
        {
            temp = '0' - date[2];
            temp2 = '0' - date[3];
            d2 = temp * 10 + temp2;
            d2 *= -1;
        }
        else if (date[2] == '/' && date[4] == '/')
        {
            d2 = ('0' - date[3]) * -1;
        }
        else if (date[2] == '/' && date[5] == '/')
        {
            temp = ('0' - date[3]);
            temp2 = '0' - date[4];
            d2 = temp2 + temp * 10;
            d2 *= -1;
        }
        //the year only matters where the slash is and there are 4 possible places after that the year
        //is always four digits, so i use exponential addition to add them
        if (date[3] == '/')
        {
            y3 = (('0' - date[4]) * 1000 + ('0' - date[5]) * 100 + ('0' - date[6]) * 10 + ('0' - date[7])) * -1;
        }
        else if (date[4] == '/')
        {
            y3 = (('0' - date[5]) * 1000 + ('0' - date[6]) * 100 + ('0' - date[7]) * 10 + ('0' - date[8])) * -1;
        }
        else if (date[5] == '/')
        {
            y3 = (('0' - date[6]) * 1000 + ('0' - date[7]) * 100 + ('0' - date[8]) * 10 + ('0' - date[9])) * -1;
        }
        Date iii(m1, d2, y3);
        if (iii.month == m1 || iii.day == d2 || iii.year == y3)
        {
            illegal = false;
        }
        else
        {
            illegal = true;;
            cout << "Invalid date. Try again" << endl;
        }
    }
    while (illegal == true);
}

//returns the month in number value
int Date::GetMonth() const
{
    return month;
}
//returns the dat in number value
int Date::GetDay() const
{
    return day;
}
//returns the year in number value
int Date::GetYear() const
{
    return year;
}
//same as the constructor, except if false, doesn't change anything
bool Date::Set(int m, int d, int y)
{
    int century;
    bool error;
    //needed for leap year
    if (y % 1000 == 0)
    {
        century = y;
    }
    //Month error check
    if (m < 1 || m > 12)
    {
        error = true;
    }
    //Year error check
    if (y < 1900)
    {
        error = true;
    }
    //Day less than 0 Check
    if (d <= 0)
    {
        error = true;
    }
    //Error check for correct day for each month
    switch (m)
    {

        case 2:
            if (d > 28)
            {
                error = true;
            }
            if (d == 29 && (y % 4 == 0 || century % 400 == 0))
            {
                d = 29;
            }
            break;
        case 4:
        case 6:
        case 11:
            if (d > 30)
            {
                error = true;
            }
            break;
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            if (d > 31)
            {
                error = true;
            }
            break;
    }
    //Assigning values to Private class
    //if there is no error change private variables, if there is error dont change
    if (error == false)
    {
        day = d;
        month = m;
        year = y;
        return true;
    }
    else
    {
        return false;
    }
}

//increments the day by 1 and changes the month if the day goes over the month
void Date::Increment()
{
    int m, d, y;
    m = month;
    d = day;
    y = year;

    d++;

    int century;
    //needed for leap year
    if (y % 1000 == 0)
    {
        century = y;
    }


    //Error check for correct day for each month
    //Switch statement for different months because some months have different days
    switch (m)
    {
        case 2:
            if (d == 29 && (y % 4 == 0 || century % 400 == 0))
            {
                d = 29;
            }
            else if (d > 28)
            {
                m++;
                d = 1;
            }
            break;
        case 4:
        case 6:
        case 11:
            if (d > 30)
            {
                m++;
                d = 1;
            }
            break;
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            if (d > 31)
            {
                //checks so if the month is 12, change hte month to 1 instead of 13
                if (m != 12)
                {
                    m++;
                }
                else
                {
                    m = 1;
                }
                d = 1;
            }
            break;
    }
    //Assigning values to Private class
    day = d;
    month = m;
    year = y;
}

//returns a value 0-6 0 being sunday and 6 being Friday
int Date::DayofWeek()
{
    //this function was given to us
    int d, y, m;

    y = year;
    m = month;
    d = day;

    static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
    y -= m < 3;
    return ((y + y / 4 - y / 100 + y / 400 + t[m - 1] + d) % 7);
}

//compares the current date with another date and returns -1 for lower
//, 0 for equal and 1 for greater
int Date::Compare(const Date &d)
{
    int d1, m1, y1, d2, m2, y2;
    d1 = day;
    m1 = month;
    y1 = year;

    d2 = d.day;
    m2 = d.month;
    y2 = d.year;

    if (y1 > y2)
    {
        return 1;
    }
    else if (y1 < y2)
    {
        return -1;
    }
    else
    {
        if (m1 > m2)
        {
            return 1;
        }
        else if (m1 < m2)
        {
            return -1;
        }
        else
        {
            if (d1 > d2)
            {
                return 1;
            }
            else if (d1 < d2)
            {
                return -1;
            }
            else
            {
                return 0;
            }
        }
    }
}

//prints out the weekday with the month, day, and year.
void Date::ShowByDay()
{
    //usese the day of the week member function to accurately get the right answer
    switch (Date::DayofWeek())
    {
        case 0:
            cout << "Sunday " << month << "/" << day << "/" << year;
            break;
        case 1:
            cout << "Monday " << month << "/" << day << "/" << year;
            break;
        case 2:
            cout << "Tuesday " << month << "/" << day << "/" << year;
            break;
        case 3:
            cout << "Wednesday " << month << "/" << day << "/" << year;
            break;
        case 4:
            cout << "Thursday " << month << "/" << day << "/" << year;
            break;
        case 5:
            cout << "Friday " << month << "/" << day << "/" << year;
            break;
        case 6:
            cout << "Saturday " << month << "/" << day << "/" << year;
            break;
    }
    cout << "\n";
}

//shows the date by the month and all its days
void Date::ShowByMonth()
{

    int y = year;
    //uses a temp date so it can accurately calculate how many
    //spaces is needed for the month
    Date temp(month, 1, year);
    //number of spaces is equal to the week day number
    int numspace = temp.DayofWeek();
    bool leapyear = false;
    const string space = "      ";
    const string HEADER = "Su    Mo    Tu    We    Th    Fr    Sa";
    cout << HEADER << endl;


    int century;
    //needed for leap year
    if (y % 1000 == 0)
    {
        century = y;
    }
    if (y % 4 == 0 || century % 400 == 0)
    {
        leapyear = true;
    }

    switch (month)
    {
        //for these months they end in 31 days so the space is caluclated and
        //modulus is used so it wraps around correctly;
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            for (int i = 1, wrap = (i + numspace); i <= 31; i++)
            {
                if (i == 1)
                {
                    for (int j = 0; j < numspace; j++)
                    {
                        cout << space;
                    }
                }
                if (i < 10)
                {
                    cout << "0" << i << "    ";
                }
                else if (i > 10 && i < 20)
                {
                    cout << i << "    ";
                }
                else if (i > 20 && i < 30)
                {
                    cout << i << "    ";
                }
                else
                {
                    cout << i << "    ";
                }

                if (wrap % 7 == 0)
                {
                    cout << "\n";
                }
                wrap++;
            }
            break;
        //february needs its own because it has a leap year that needs to be accounted
        //for, so thats in a vairable that changes the number it goes to based
        //if its a leap year or not.
        case 2:
            int leap;
            if (leapyear == true)
            {
                leap = 29;
            }
            else
            {
                leap = 28;
            }

            for (int i = 1, wrap = (i + numspace); i <= leap; i++)
            {
                if (i == 1)
                {
                    for (int j = 0; j < numspace; j++)
                    {
                        cout << space;
                    }
                }

                if (i < 10)
                {
                    cout << "0" << i << "    ";
                }
                else if (i > 10 && i < 20)
                {
                    cout << i << "    ";
                }
                else if (i > 20 && i < 30)
                {
                    cout << i << "    ";
                }
                else
                {
                    cout << i << "    ";
                }

                if (wrap % 7 == 0)
                {
                    cout << "\n";
                }
                wrap++;
            }
            break;
        //these months end in 30 days
        case 4:
        case 6:
        case 11:
            for (int i = 1, wrap = (i + numspace); i <= 30; i++)
            {
                if (i == 1)
                {
                    for (int j = 0; j < numspace; j++)
                    {
                        cout << space;
                    }
                }
                if (i < 10)
                {
                    cout << "0" << i << "    ";
                }
                else if (i > 10 && i < 20)
                {
                    cout << i << "    ";
                }
                else if (i > 20 && i < 30)
                {
                    cout << i << "    ";
                }
                else
                {
                    cout << i << "    ";
                }

                if (wrap % 7 == 0)
                {
                    cout << "\n";
                }
                wrap++;
                break;
            }
    }
    cout << endl;
}