Code:
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#define START_GREGORIAN_CALENDAR 1582
#define THURSDAY (0)
#define FRIDAY (1)
#define SATURDAY (2)
#define SUNDAY (3)
#define MONDAY (4)
#define TUESDAY (5)
#define WEDNESDAY (6)
//Function prototypes
int dayOfWeek(int doomsday, int leapYear, int month, int day);
int isLeapYear(int year);
int yearToDoomsday(int year);
int daysToNextThursday(int year, int month, int day);
int isValidYear(int year);
//Main function
int main(int argc, char* argv[]){
int dayName = 0;
int day = 0;
int month = 0;
int year = 0;
int doomsday = 0;
int leapYear = 0;
printf("Enter a date after 1582 in dd mm yyyy form: \n");
scanf("%d", &day);
scanf("%d", &month);
scanf("%d", &year);
assert(year >= START_GREGORIAN_CALENDAR);
//Checking for leap year
if(isValidYear(year)) {
leapYear = isLeapYear(year);
doomsday = yearToDoomsday(year);
dayName = dayOfWeek(doomsday, leapYear, month, day);
printf("\nThe day of the week is ");
if(dayName%7 == 0){
printf("Thurs");
}
if(dayName%7 == 1){
printf("Fri");
}
if(dayName%7 == 2){
printf("Satur");
}
if(dayName%7 == 3){
printf("Sun");
}
if(dayName%7 == 4){
printf("Mon");
}
if(dayName%7 == 5){
printf("Tues");
}
if(dayName%7 == 6){
printf("Wednes");
}
printf("day!\n");
daysToNextThursday(year, month, day);
}
return EXIT_SUCCESS;
}
//Function to determine leap year
int isValidYear(int year) {
int yearIsValid = 0;
if (year >= START_GREGORIAN_CALENDAR){
yearIsValid = 1;
if(isLeapYear(year)){
printf("\nThe year %d is a leap year.\n", year);
} else {
printf("\nThe year %d is not a leap year.\n", year);
}
} else {
printf("Year is before 1582.\n");
}
return yearIsValid;
}
int isLeapYear(int year){
int isLeap = 0;
if(year%400 == 0){
isLeap = 1;
} else if(year%100 == 0){
isLeap = 0;
} else if(year%4 == 0){
isLeap = 1;
} else if(year%4 != 0){
isLeap = 0;
}
return isLeap;
}
//Doomsday function
int yearToDoomsday(int year){
int whatday = 0;
whatday = (TUESDAY) + (year) + (year/4) - (year/100) + (year/400);
int doomsday;
doomsday = (whatday%7);
printf("\nThe doomsday is %d days from Thursday.\n", doomsday);
return doomsday;
}
//Day of week function
int dayOfWeek(int doomsday, int leapYear, int month, int day){
int doomsdate = 0;
int dayofweek = 0;
//Setting doomsday date
if(month == 2){
if(leapYear){
doomsdate = 29;
} else {
doomsdate = 28;
}
} else if(month%2 == 0){
doomsdate = month;
} else if(month%2 != 0){
if(month == 7){
doomsdate = 11;
} else if(month == 11){
doomsdate = 7;
} else if(month == 9){
doomsdate = 5;
} else if(month == 5){
doomsdate = 9;
} else if(month == 3){
doomsdate = 7;
} else if(month == 1){
if(leapYear){
doomsdate = 4;
} else {
doomsdate = 3;
}
}
}
if (day > doomsdate){
dayofweek = 7 - doomsday + ((day-doomsdate)%7);
} else if (day < doomsdate){
dayofweek = 7 - doomsday + 7 - ((doomsdate - day)%7);
} else {
dayofweek = 7 - doomsday;
}
dayofweek = dayofweek%7 + 1;
return dayofweek;
}
//Function to determine number of days till next Thursday
int daysToNextThursday (int year, int month, int day){
int dayofweek;
int daysToGo;
daysToGo = (7 - dayofweek);
printf("\nThere are %d days until next Thursday.\n", daysToGo);
return daysToGo;
}I'm currently taking a computing course and we've just been learning how to do basic things in C.
I'm supposed to write a program which determines the day of the week given a certain input, after working out whether or not it is a leap year and the doomsday for that year.
I've run into a problem with my code with the last part, it always prints out "There are 7 days until next Thursday" when it shouldn't ._.
Would anyone care to point out my mistake?
Thanks in advance
