#include #include typedef struct { int day, month, year; } date ; int DifferentDate( date d1, date d2 ) { int n1, n2 d1.month = (d1.month + 9) % 12; d1.year = d1.year - d1.month / 10; n1= 365*d1.year + d1.year/4 - d1.year/100 + d1.year/400 + (d1.month*306 + 5)/10 + ( d1.day - 1 ); d2.month = (d2.month + 9) % 12; d2.year = d2.year - d2.month / 10; n2= 365*d2.year + d2.year/4 - d2.year/100 + d2.year/400 + (d2.month*306 + 5)/10 + ( d2.day - 1 ); return n1 - n2; } // Function to check leap year. //Function returns 1 if leap year int IsLeapYear(int year) { return (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0)); } // returns 1 if given date is valid. int isValidDate(date d) { //check range of year,month and day if (d.year > 2100 || d.year < 1900) return 0; if (d.month < 1 || d.month > 12) return 0; if (d.day < 1 || d.day > 31) return 0; //Handle feb days in leap year if (d.month == 2) { if (IsLeapYear(d.year)) return (d.day <= 29); else return (d.day <= 28); } //handle months which has only 30 days if (d.month == 4 || d.month == 6 || d.month == 9 || d.month == 11) return (d.day <= 30); return 1; } int compare_dates (date d1, date d2) { if (d1.year < d2.year) return -1; else if (d1.year > d2.year) return 1; if (d1.year == d2.year) { if (d1.monthd2.month) return 1; else if (d1.dayd2.day) return 1; else return 0; } } int main (){ date d1 , d2; int status_d1=0, status_d2=0; int check_2_status=0; // ================================ INPUT ================================ printf("This program calculates the number of days that passed between two dates."); printf("You should enter day then month then year like DAYS MONTH YEAR\n\n"); printf("Enter the first date :\n"); scanf("%d/%d/%d", &d1.day, &d1.month, &d1.year); printf("Enter the second date (Date 2 should be <= Date 1):\n"); scanf("%d/%d/%d", &d2.day, &d2.month, &d2.year); // ======================================================================== // display what you have enter printf("\nDate 1:%d/%d/%d\n",d1.day, d1.month, d1.year); printf("Date 2:%d/%d/%d\n\n",d2.day, d2.month, d2.year); // ================================ CHECK ================================= printf(" --------\n"); printf("| CHECKS |\n"); printf(" --------\n"); // 1. check if date is valid printf("CHECK 1 : (check if dates are dd:[0-31], mm:[1-12], yyyy:[1900-2100])\n"); status_d1 = isValidDate(d1); status_d2 = isValidDate(d2); if(status_d1 == 1){ printf("Date 1 is valid.\n"); }else{ printf("Date 1 is invalid.\n"); return -1; } if(status_d2 == 1){ printf("Date 2 is valid.\n\n"); }else{ printf("Date 2 is invalid.\n\n"); return -1; } // 2. check if date2 is less than date 1 printf("CHECK 2 : (check if date2 <= date1)\n"); check_2_status = compare_dates (d1, d2); switch(check_2_status) { case -1: printf("%d/%d/%d is earlear date than %d/%d/%d\n\n", d1.day, d1.month, d1.year, d2.day, d2.month, d2.year); return -1; break; case 1: printf("%d/%d/%d is later date than %d/%d/%d\n\n", d1.day, d1.month, d1.year, d2.day, d2.month, d2.year); break; case 0: printf("%d/%d/%d is the same date than %d/%d/%d\n\n", d1.day, d1.month, d1.year, d2.day, d2.month, d2.year); break; } // ================================ END OF CHECKS ================================= printf(" --------\n"); printf("| RESULT |\n"); printf(" --------\n"); printf("Dates difference in days is : %d",DifferentDate(d1,d2)); return 0; }

the NUmber of days passed between two dates