Take the day, month and year as input and determine whether the date entered is valid or not.

#include <stdio.h>

int main(void)
{
int day, month, year;

printf("\nEnter Date ( dd mm yy ) : ");
scanf("%d%d%d", &day, &month, &year);

if((day >= 1 && day <= 31) &&
(month == 1 || month == 3 || month == 5 || month == 7 ||
month == 8 || month == 10 || month == 12) &&
(year >= 1))
{
printf("%d / %d / %d is a valid date", day, month, year);
}
else if((day >= 1 && day <= 30) &&
(month == 4 || month == 6 || month == 9 || month == 11) &&
(year >= 1))
{
printf("%d / %d / %d is a valid date", day, month, year);
}
else if((day >= 1 && day <= 29) && (month == 2) &&
(year >= 1) &&
((year % 100 == 0 && year % 400 == 0) ||
(year % 100 != 0 && year % 4 == 0)))
{
printf("%d / %d / %d is a valid date", day, month, year);
}
else if((day >= 1 && day <= 28) && (month == 2))
{
printf("%d / %d / %d is a valid date", day, month, year);
}

else
{
printf("Invalid date");
}

return 0;
}