Hi.
A few weeks a go a post some code to calculate the day of the week of a particular date. It was just an idea. I had to sit down and code it. Here you have it:
Code:#include <stdio.h> char *day[] = {"Friday","Saturday","Sunday","Monday","Tuesday","Wednesday", "Thursday"}; int day_of_month[] = {31,28,31,30,31,30,31,31,30,31,30,31}; int day_of_week(int, int, int); int leap (int); void instructions(void); int d, m, a; int main () { instructions(); do { printf("\nEnter date -> "); scanf("%d%d%d",&d, &m, &a); printf("%d %d %d\n", d, m, a); printf ("\nThe day of the week is %s \n", day[day_of_week(d,m,a)]); } while ( (d!=0) && (m!=0) && (a!=0) ); } int day_of_week(int d, int m, int a) { int xa, i; int days_counter = 0; // Compute days from begining of era to december 31 of year a-1 for (xa = 0; xa < a; xa++) if (leap(xa)) days_counter += 366; else days_counter += 365; // Compute days from months before m for (i=0; (i+1) < m; i++) days_counter += day_of_month[i]; // compute the remaining days days_counter+= d; // See if a is leap year and if so, see if date is after february // Add 1 if so. if ( (m > 2) && (leap(a))) days_counter += 1; return ( (int) (days_counter % 7) ); // return the remainder } int leap(int x) { if ( (x % 400) == 0 ) // is leap return (1); else if ( (x % 100) == 0 ) // it's not leap return (0); else if ( (x % 4) == 0 ) return (1); // is leap else return (0); // it's not leap } void instructions(void) { printf("This program computes the day of the week of a particular\n"); printf("date. The date must be entered in the form dd mm yyyy.\n"); printf("It should be separated by spaces. Example October 12 1492,\n"); printf("should be entered as : 12 10 1492 .\n"); printf("1. the program will give an answer even if the date does not exist.\n"); printf("2. the program only works for dates after Christ.\n"); printf("3. try the day you were born!\n"); }
