Determine whether a given date is valid or not.

#include <stdio.h>

int isValidDate(int,int,int);
int isLeap(int);

int main(void)
{
int d, m, y;

printf("\nEnter date (d/m/y) : ");
scanf("%d%d%d", &d, &m, &y);

if(isValidDate(d,m,y))
printf("\n%d / %d / %d is a valid date", d, m, y);
else
printf("\n%d / %d / %d is NOT a valid date", d, m, y);

return 0;
}

int isValidDate(int day,int month,int year)
{
if(year >= 1)
{
if((day >= 1 && day <= 31) &&
(month == 1 || month == 3 || month == 5 || month == 7 ||
month == 8 || month == 10 || month == 12))
{
return 1;
}
else if((day >= 1 && day <= 30) &&
(month == 4 || month == 6 || month == 9 || month == 11))
{
return 1;
}
else if((day >= 1 && day <= 29) && (month == 2) && isLeap(year))
{
return 1;
}
else if((day >= 1 && day <= 28) && (month == 2))
{
return 1;
}
}

return 0;
}

int isLeap(int year)
{
return (year % 100 == 0 && year % 400 == 0) ||
(year % 100 != 0 && year % 4 == 0) ? 1 : 0;
}