C++ Program That Displays The Calendar

Name:  Calendar

Description of the Program: This program displays todays date and time and the calendar from the year 2000 up to the year you want.

As you can see in the screenshot below, before you will enter the year, the program will display the current date and time. Then, I entered the year 2020 and the month 2 which corresponds to the month of February. Then, it displayed the full calendar of the year 2020 from Sunday to Saturday with their corresponding dates.

 

//Below are the Codes of the Program:

#include<dos.h>
#include<iostream.h>
#include<conio.h>
#include<process.h>
#include<time.h>
/* This Class is used for generating calendar */
class calen
{
 int days; /* Will have no. of days a month has */
 int mm; /* Month Iterator variable [1-12] */
 int k; /* Days Iterator [ 0 till the days in month ] */
 int z; /* Iterator Variable */
 int p; /* Start day of every month e.g. 5 for friday */
 int yy; /* User Entered year */
 int r; /* Year Iterator variable */
 int calen[5][7]; /* The Matrix stores all required dates */
 int i,j; /* Iterator Variables */
 int mon; /* User entered month */
 public:
 void calen_call(void);
 void display(void);
};

void main()
{
 clrscr();
 calen c;
 c.calen_call();
 c.display();
 getch();
}

void calen::calen_call(void)
{

 int month[12]={31,28,31,30,31,30,31,31,30,31,30,31};

 time_t t;
 time(&t);
 cout<<"\n\n\n\t\t\tCALENDAR FROM YEAR 2000...\n\n\n";
 cout<<"\n\nTODAY'S DATE AND TIME: "<<ctime(&t);
 repeat:

 cout<<"\n\nENTER YEAR [2000 ...] : ";
 cin>>yy;

 if(yy<=1999)
 {
    cout<<"\n\nWRONG ENTRY";

    goto repeat;
 }

 if(yy%4==0)
 {
    if(yy%100==0)
    {
     if(yy%400==0)
     month[1]=29;
     else
     month[1]=28;
    }
    else
    month[1]=29;
 }

 again:
 cout<<"\nENTER MONTH [1-12] :";
 cin>>mon;

 if(mon>12||mon<1)
 {
    cout<<"\nWRONG ENTRY";

    goto again;
 }

 cout<<"\n\n\t\t\t\tYEAR "<<yy<<"\n\n";

 switch(mon)
 {
    case 1:cout<<"\n\n\t\t\t\tJANUARY\n\n";break;
    case 2:cout<<"\n\n\t\t\t\tFEBRUARY\n\n";break;
    case 3:cout<<"\n\n\t\t\t\tMARCH\n\n";break;
    case 4:cout<<"\n\n\t\t\t\tAPRIL\n\n";break;
    case 10:cout<<"\n\n\t\t\t\tOCTOBER\n\n";break;
    case 11:cout<<"\n\n\t\t\t\tNOVEMBER\n\n";break;
    case 5:cout<<"\n\n\t\t\t\tMAY\n\n";break;
    case 6:cout<<"\n\n\t\t\t\tJUNE\n\n";break;
    case 7:cout<<"\n\n\t\t\t\tJULY\n\n";break;
    case 8:cout<<"\n\n\t\t\t\tAUGUST\n\n";break;
    case 9:cout<<"\n\n\t\t\t\tSEPTEMBER\n\n";break;
    case 12:cout<<"\n\n\t\t\t\tDECEMBER\n\n";break;
    default:cout<<"\n\nWRONG ENTRY";exit(0);
 }
 /* Start day of year 1999 i.e. Friday 1st January 1999 */
 p=5;
 /* Determination of start day of entered year [Calculating from 1999] */
 for(r=1999;r<yy;r++)
 {
    if(r%4==0)
    {
     if(r%100==0)
     {
        if(r%400==0)
        p=p+2;
        else
        p++;
     }
     else
     p=p+2;
    }
    else
    p++;
    /* Resseting of start variable if last day is reached */
    if(p==7)
    p=0;
    if(p==8)
    p=1;
 }
 /* Start of Month iteration for entered year */
 for(mm=0;mm<12;mm++)
 {
    /* Number of days a month has. Takes from the array defined above */
    days=month[mm];
    /* Start of days from */
    k=0;
    /* Setting all values in first row to 0 */
    for(z=0;z<7;z++)
    calen[0][z]=0;
    /* Looping through the rows and columns of calen */
    for(i=0;i<5;i++,p=0)
    for(j=p;j<7&&k<days;j++)
    {
     /* Adding of days to the matrix */
     calen[i][j]=k+1;
     k++;
     /* Checking for finish of days */
     if(k==days&&i==4&&j<7)
     {
        /* Setting of remaining values to 0 */
        for(p=j+1;p<7;p++)
        calen[i][p]=0;
     }
     /* Putting values on first row if matrix is finished */
     if(k<days&&i==4&&j==6)
     {
        for(p=0;p<7&&k<days;p++,k++)
        calen[0][p]=k+1;
        j=p-1;
     }
     /* Setting of j to -1 when days are finished */
     if(k==days&&i==4&&j==6)
     {
        j=-1;
     }
     /* Special Check if days finish in 4th row e.g. 2009 february */
     if(k==days&&i==3&&j==6)
     {
        /* Setting of final row to 0 */
        for(p=0;p<7;p++)
        calen[4][p]=0;
     }
    }
    /* Resetting of start day for next month */
    p=j;
    /* Returning of loop if desired month is found */
    if(mm+1==mon)
    return;
 }
}
/* Displays the values of Calen array */
void calen::display()
{
 /* Printing of day names */
 cout<<"\n\tSUN\tMON\tTUE\tWED\tTHU\tFRI\tSAT\n\n";
 /* Start of loop of rows */
 for(i=0;i<5;i++)
 {
    /* Start of loop of columns */
    for(j=0;j<7;j++)
    cout<<"\t"<<calen[i][j];
    cout<<"\n\n";
 }

 getch();
}

Screenshot of the Program: