# C Program to Check Whether a Year is Leap Year or Not

A year that has 366 days is called a leap year.

A year can be checked whether a year is leap year or not by dividing the year by 4, 100 and 400. If a number is divisible by 4 but not by 100 then, it is a leap year. Also, if a number is divisible by 4, 100 and 400 then it is a leap year. Otherwise the year is not a leap year.

### Example 1: Source Code to Check Leap Year

```#include <stdio.h>

int yr;
printf ("Enter a year \n");
scanf ("%d", &yr);

if (yr%4 == 0) {

if(yr%100 == 0) {

if(yr%400 == 0)
printf("\n It is LEAP YEAR.");
else
printf("\n It is NOT LEAP YEAR.");
}

else {
printf ("\n It is LEAP YEAR.");
}
}
else
printf("\n It is NOT LEAP YEAR.");

return 0;
```

Here, the year entered by the user is firstly divided by 4. If it is divisible by 4 then it is divided by 100 and then 400. If year is divisible by all 3 numbers then that year is a leap year. If the year is divisible by 4 and 100 but not by 400 then it is not a leap year. If the year is divisible by 4 but not by 100, then it is a leap year. (Remember that if the year is divisible by 4 and not by hundred then the program does not check the last condition, i.e., whether the year is divisible by 400). If the year is not divisible by 4 then no other conditions are checked and the year is not a leap year.

### Example 2: Source Code to Check Leap Year

```#include <stdio.h>

int main()
{
int yr;
printf ("Enter a year \n");
scanf ("%d", &yr);

if (yr%4 == 0 && yr%100 == 0 && yr%400 == 0)
printf("\n It is LEAP YEAR.");

else if (yr%4==0 && yr%100!=0)
printf("\n It is LEAP YEAR.");
else
printf ("\n It is NOT LEAP YEAR.");

return 0;
}
```

​Here, if the year is divisible by 4, 100 and 400 then “It is LEAP YEAR.”  is displayed. If the year is divisible by 4 but not by 100 then “It is LEAP YEAR.” is displayed. Otherwise, “It is NOT LEAP YEAR” is displayed.

Output:

```Enter a year
1600
It is LEAP YEAR.
```
```Enter a year
2900
It is NOT LEAP YEAR.
```