Printing a Calendar of a given year using C++

In this article, we are going to learn how we can print a calendar for a given year using basic C++ language.

Below function dayNumber() takes the day, month, and year as a parameter returns the start day of every month i.e returns 0-Sunday,1-Monday, and so on.

int dayNumber(int day, int month, int year) 
{   
  static int t[] = { 0, 3, 2, 5, 0, 3, 5, 1,4, 6, 2, 4 }; 
    year -= month < 3; 
    /*Proven formula for finding the starting day of month*/
    return ( year + year/4 - year/100 + 
             year/400 + t[month-1] + day) % 7; 
}

We have created a function getMonthName() which returns a string for input month number i.e, 0-January, 1-February, and so on

string getMonthName(int monthNumber) 
{ 
    string months[] = {"January", "February", "March", 
                       "April", "May", "June", 
                       "July", "August", "September", 
                       "October", "November", "December"
                      }; 
  
    return (months[monthNumber]); 
}

Now, we just need to find the number of days in the month according to the year (for example, a leap year has 29 days in February month and 28 days for the normal year)

We have created a function that returns a number of days.

int numberOfDays (int monthNumber, int year) 
{ 
  int month[]={31,28,31,30,31,30,31,31,30,31,30,31};
  if (monthNumber == 1) 
    { 
        /*If the year is leap then February has 29 days*/ 
        if (year % 400 == 0 || 
                (year % 4 == 0 && year % 100 != 0)) 
            month[1]=29; 
    } 
    return month[monthNumber];
}

We are almost done, we just need to print the calendar. Here is the code for printing the calendar.

void printCalendar(int year) 
{ 
    printf ("\n\n         Calendar - %d\n\n", year); 
    int days; 
    int current = dayNumber (1, 1, year); 
    for (int i = 0; i < 12; i++) 
    { 
        days = numberOfDays (i, year); 
        printf("\n  ------------%s-%d-------------\n", getMonthName (i).c_str(),year);
        printf("  Sun  Mon  Tue  Wed  Thu  Fri  Sat\n"); 
        int k; 
        for (k = 0; k < current; k++) 
            printf("     "); 
  
        for (int j = 1; j <= days; j++) 
        { 
            printf("%5d", j); 
            if (++k > 6) 
            { 
                k = 0; 
                printf("\n"); 
            } 
        } 
  
        if (k) 
            printf("\n"); 
  
        current = k; 
    }  
}

In this way, you can print a Calendar by using C++ language. I hope it was easy enough to understand. If you have any doubt, feel free to ask in the comment section. All the best!