Built-in method

Leap
Leap in C# 
using System; // for DateTime

public static bool IsLeapYear(int year)
{
    return DateTime.IsLeapYear(year);
}

This may be considered a "wicked cheat" for this exercise, by simply passing the year into the IsLeapYear method of the DateTime struct. Although it is not in the spirit of this exercise, IsLeapYear would be the idiomatic way to determine if a year is a leap year in the "real world".

Shortening

When the body of a function is a single expression, the function can be implemented as an expression-bodied member, like so

public static bool IsLeapYear(int year) =>
    DateTime.IsLeapYear(year);

or

public static bool IsLeapYear(int year) => DateTime.IsLeapYear(year);
24th Apr 2024 · Found it useful?

Other Approaches to Leap in C#

Other ways our community solved this exercise
public static bool IsLeapYear(int year)
{
    return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}
Boolean chain

Use a chain of boolean expressions. 

public static bool IsLeapYear(int year)
{
    return year % 100 == 0 ? year % 400 == 0 : year % 4 == 0;
}
Ternary operator

Use a ternary operator of boolean expressions. 

return (year % 4, year % 100, year % 400) switch
{
    (_, 0, 0) => true,
    (_, 0, _) => false,
    (0, _, _) => true,
    _ => false,
};
switch on a tuple

Use a switch on a tuple made from boolean expressions. 

public static bool IsLeapYear(int year)
{
    return (new DateTime(year, 2, 28)).AddDays(1.0).Day == 29;
}
DateTime addition

Use DateTime addition.