How to Check if a Year Is a Leap Year in Multiple Languages

A leap year is a year that has 366 days. An additional day is added to the leap year to keep the calendar year synchronized with the astronomical year. You can check if a given year is a leap year or not using mathematics and programming.

In this article, you’ll learn how to check whether the given year is a leap year or not using C++, Python, JavaScript, and C.

Problem Statement

You’re given a year. You need to check whether the given year is a leap year or not.

Example 1: Let year = 2021.

2021 is not a leap year.

Thus, the output is “2021 is not a leap year”.

Example 2: Let year = 1980.

1980 is a leap year.

Thus, the output is “1980 is a leap year”.

Condition for a Year to Be a Leap Year

A year is a leap year if any or both of the following conditions are satisfied:

1. The year is a multiple of 400.
2. The year is a multiple of 4 and not a multiple of 100.

C++ Program to Check Whether a Year Is a Leap Year or Not

Below is the C++ program to check whether a given year is a leap year or not:

// C++ program to check if a given year is a leap year or not
#include 
using namespace std;
bool isLeapYear(int y)
{
 // If a year is a multiple of 4 and not a multiple of 100 or a multiple of 400, 
 // then the year is a leap year
 // Multiple of 4 and (Not a multiple of 100 or Multiple of 400) => A Leap year
 return (((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0));
}
int main()
{
 int year1 = 2021;
 cout  if(isLeapYear(year1))
 {
 cout  }
 else
 {
 cout  }
int year2 = 2012;
 cout  if(isLeapYear(year2))
 {
 cout  }
 else
 {
 cout  }
int year3 = 1980;
 cout  if(isLeapYear(year3))
 {
 cout  }
 else
 {
 cout  }
int year4 = 1990;
 cout  if(isLeapYear(year4))
 {
 cout  }
 else
 {
 cout  }
int year5 = 1600;
 cout  if(isLeapYear(year5))
 {
 cout  }
 else
 {
 cout  }
return 0;
}

Output:

Year: 2021
2021 is not a leap year
Year: 2012
2012 is a leap year
Year: 1980
1980 is a leap year
Year: 1990
1990 is not a leap year
Year: 1600
1600 is a leap year

Related: What Is a Fibonacci Sequence and How Do You Print One in Python, C++, and JavaScript?

Python Program to Check Whether a Year Is a Leap Year or Not

Below is the Python program to check whether a given year is a leap year or not:

# Python program to check if a given year is a leap year or not
def isLeapYear(y):
    # If a year is a multiple of 4 and not a multiple of 100 or a multiple of 400,
    # then the year is a leap year
    # Multiple of 4 and (Not a multiple of 100 or Multiple of 400) => A Leap year
    return (((y % 4 == 0) and (y % 100 != 0)) or (y % 400 == 0))

year1 = 2021
print("Year: ", year1)
if isLeapYear(year1):
    print(year1, "is a leap year")
else:
    print(year1, "is not a leap year")
year2 = 2012
print("Year: ", year2)
if isLeapYear(year2):
    print(year2, "is a leap year")
else:
    print(year2, "is not a leap year")
year3 = 1980
print("Year: ", year3)
if isLeapYear(year3):
    print(year3, "is a leap year")
else:
    print(year3, "is not a leap year")
year4 = 1990
print("Year: ", year4)
if isLeapYear(year4):
    print(year4, "is a leap year")
else:
    print(year4, "is not a leap year")
year5 = 1600
print("Year: ", year5)
if isLeapYear(year5):
    print(year5, "is a leap year")
else:
    print(year5, "is not a leap year")

Related: How to Print “Hello, World!” in the Most Popular Programming Languages

JavaScript Program to Check Whether a Year Is a Leap Year or Not

Below is the JavaScript program to check whether a given year is a leap year or not:

// JavaScript program to check if a given year is a leap year or not
function isLeapYear(y) {
 // If a year is a multiple of 4 and not a multiple of 100 or a multiple of 400, 
 // then the year is a leap year
 // Multiple of 4 and (Not a multiple of 100 or Multiple of 400) => A Leap year
 return (((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0));
}

var year1 = 2021;
document.write("Year: " + year1 + "
");
if(isLeapYear(year1)) {
 document.write(year1 + " is a leap year" + "
");
} else {
 document.write(year1 + " is not a leap year" + "
");
}
var year2 = 2012;
document.write("Year: " + year2 + "
");
if(isLeapYear(year2)) {
 document.write(year2 + " is a leap year" + "
");
} else {
 document.write(year2 + " is not a leap year" + "
");
}
var year3 = 1980;
document.write("Year: " + year3 + "
");
if(isLeapYear(year3)) {
 document.write(year3 + " is a leap year" + "
");
} else {
 document.write(year3 + " is not a leap year" + "
");
}
var year4 = 1990;
document.write("Year: " + year4 + "
");
if(isLeapYear(year4)) {
 document.write(year4 + " is a leap year" + "
");
} else {
 document.write(year4 + " is not a leap year" + "
");
}
var year5 = 1600;
document.write("Year: " + year5 + "
");
if(isLeapYear(year5)) {
 document.write(year5 + " is a leap year" + "
");
} else {
 document.write(year5 + " is not a leap year" + "
");
}

Output:

Year: 2021
2021 is not a leap year
Year: 2012
2012 is a leap year
Year: 1980
1980 is a leap year
Year: 1990
1990 is not a leap year
Year: 1600
1600 is a leap year

Related: Functional Programming Languages You Should Know

C Program to Check Whether a Year Is a Leap Year or Not

Below is the C program to check whether a given year is a leap year or not:

// C program to check if a given year is a leap year or not
#include 
#include 
bool isLeapYear(int y)
{
 // If a year is a multiple of 4 and not a multiple of 100 or a multiple of 400, 
 // then the year is a leap year
 // Multiple of 4 and (Not a multiple of 100 or Multiple of 400) => A Leap year
 return (((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0));
}
int main()
{
 int year1 = 2021;
 printf("Year: %d ⁠n", year1);
 if(isLeapYear(year1))
 {
 printf("%d is a leap year ⁠n", year1);
 }
 else
 {
 printf("%d is not a leap year ⁠n", year1);
 }
int year2 = 2012;
 printf("Year: %d ⁠n", year2);
 if(isLeapYear(year2))
 {
 printf("%d is a leap year ⁠n", year2);
 }
 else
 {
 printf("%d is not a leap year ⁠n", year2);
 }
int year3 = 1980;
 printf("Year: %d ⁠n", year3);
 if(isLeapYear(year3))
 {
 printf("%d is a leap year ⁠n", year3);
 }
 else
 {
 printf("%d is not a leap year ⁠n", year3);
 }
int year4 = 1990;
 printf("Year: %d ⁠n", year4);
 if(isLeapYear(year4))
 {
 printf("%d is a leap year ⁠n", year4);
 }
 else
 {
 printf("%d is not a leap year ⁠n", year4);
 }
int year5 = 1600;
 printf("Year: %d ⁠n", year5);
 if(isLeapYear(year5))
 {
 printf("%d is a leap year ⁠n", year5);
 }
 else
 {
 printf("%d is not a leap year ⁠n", year5);
 }
return 0;
}

Output:

Year: 2021
2021 is not a leap year
Year: 2012
2012 is a leap year
Year: 1980
1980 is a leap year
Year: 1990
1990 is not a leap year
Year: 1600
1600 is a leap year

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Source: makeuseof.com