Curious to know how you can add a double quote in raw strings?
No escape sequences are recognized in raw strings, so adding a backslash does not work.
Use ### to mark the start and the end of a raw string.
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println!("This is a double quote \" ");
// println!(r"This is a double quote " "); // Nope!
// println!(r"This is a double quote \" "); // Nope!
// And this works
println!(r#"This is a double quote " "#);
println!(r###"This is a double quote " "###);
Rust’s option implements Sum and Product traits too!
Use it when you want to get None if there is a None element and sum of values otherwise.
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let nums: [Option<u32>;3] = [Some(1), Some(10), None];
let maybe_nums: Option<u32> = nums.into_iter().sum();
assert_eq!(maybe_nums, None);
or sum of the values …
Rust’s option implements FromIterator too!
Use it when you want to get None if there is a None element and values otherwise.
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let cars = [Some("Porsche"), Some("Ferrari"), None];
let maybe_cars: Option<Vec<_>> = cars.into_iter().collect();
assert_eq!(maybe_cars, None);
or values …
Rust’s option implements an iterator!
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let o: Option<u32> = Some(200u32);
let mut iter = o.into_iter();
let v = iter.next();
assert_eq!(v, Some(200u32));
Why is this useful? see example.
As of 1.66, it is possible to use ..=X in patterns
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let result = 20u32;
match result {
0..=20 => println!("Included"),
21.. => println!("Sorry"),
}
Instead of manually implementing Default trait for an enum, you can derive it and explicitly tell which variant should be the default one.
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#[derive(Default)]
enum Car{
#[default]
Porsche,
Ferrari,
Skoda
}
let car = Car::default();
Use Debug trait to print enum values if needed.
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#[derive(Default,Debug)]
enum Car{
#[default]
Porsche,
Ferrari,
Skoda
}
let car = Car::default();
println!("{:?}", car);
Sometimes there is a need to zip two iterables of various lengths.
If it is known which one is longer, then use the following approach:
First one must be longer.
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let nums1 = [1, 2, 3, 4];
let nums2 = [10, 20];
for (n1, n2) in nums1
.into_iter()
.zip(nums2.into_iter().chain(std::iter::repeat(0i32)))
{
println!("{n1} - {n2}");
}
// Output:
// 1 - 10
// 2 - 20
// 3 - 0
// 4 - 0
As of 1.65, it is possible to use let statement with a refutable pattern.
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let result: Result<i32, ()> = Ok(20);
let Ok(value) = result else {
panic!("Heeeelp!!!");
};
assert_eq!(value, 20);
As of 1.65, it is possible to label plain block expression and terminate that block early.
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let result = 'block: {
let result = 20i32;
if result < 10 {
break 'block 1;
}
if result > 10 {
break 'block 2;
}
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};
assert_eq!(result, 2);
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