Date addition with chrono crate

Leap
Leap in Rust 
use chrono::{prelude::*, Duration};

pub fn is_leap_year(year: u64) -> bool {
    (Utc.ymd(year as i32, 2, 28) + Duration::days(1)).day() == 29
}
Caution

This approach may be considered a "cheat" for this exercise.

By adding a day to February 28th for the year, you can see if the new day is the 29th or the 1st. If it is the 29th, then the year is a leap year. This is done by using the Duration::days(1) method to add a day to a chrono::Date struct and comparing it to 29 with the day method.

The documentation suggests using NaiveDate instead of Date, in which case the code would be

pub fn is_leap_year_naive(year: u64) -> bool {
    (NaiveDate::from_ymd(year as i32, 2, 28) + chrono::Duration::days(1)).day() == 29
}

Running benchmarks gave similar results for Date and NaiveDate.

11th Dec 2024 · Found it useful?

Other Approaches to Leap in Rust

Other ways our community solved this exercise
pub fn is_leap_year(year: u64) -> bool {
    (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0))
}
Boolean one line

Use one line of boolean conditions. 

pub fn is_leap_year(year: u64) -> bool {
    if year % 100 == 0 {
        year % 400 == 0
    } else {
        year % 4 == 0
    }
}
Ternary operator

Use a ternary expression of boolean conditions. 

pub fn is_leap_year(year: u64) -> bool {
    match (year % 4, year % 100, year % 400) {
        (_, _, 0) => true,
        (_, 0, _) => false,
        (0, _, _) => true,
        _ => false,
    }
}
match on a tuple

Use a match on a tuple made from boolean conditions. 

use time::{Date, Duration, Month};

pub fn is_leap_year(year: u64) -> bool {
    (Date::from_calendar_date(year as i32, Month::February, 28).unwrap() + Duration::DAY).day()
        == 29
}
Date addition with time crate

Use time::Date addition.