C/C++ program to determine the day of a week

This tutorial is about finding out the corresponding day of the given date. For example, if I want to know which is the corresponding day of date 1991 March 10, then the program returns “Sunday”. There are various algorithm proposed for this. The below program is based on and valid for

Source Code

#include <stdio.h>
 
char *getName(int day){ //returns the name of the day
   switch(day){
      case 0 :return("Sunday");
      case 1 :return("Monday");
      case 2 :return("Tuesday");
      case 3 :return("Wednesday");
      case 4 :return("Thursday");
      case 5 :return("Friday");
      case 6 :return("Saturday");
      default:return("Error: Invalid Argument Passed");
   }
}
 
int getDayNumber(int dd,int mm,int yy){ //retuns the day number
    static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
    yy -= mm < 3;
    return (yy + yy/4 - yy/100 + yy/400 + t[mm-1] + dd) % 7;
}
 
int main(){
    int dd, mm, yy;
    printf("Enter day month and year (dd mm yyyy): ");
    scanf("%d%d%d", &dd, &mm, &yy);
    printf("\n The Corresponding day is %s", getName(getDayNumber(dd, mm, yy)));
}

Output :