Range in Rust

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

:timing
:sccache 1

Tips and Traps¶

Range does has the map method.
When constructing a range using m..n, an empty range is yield if $m \ge n$ . If you need a decreasing range, first construst an increasing range and then call the reverse method on it.
Module std::collections has a good summary on when to each which collection in Rust.

0..5

0..5

for i in 0..5 {
    println!("{}", i);
}

()

(0..5).for_each(|i|
    println!("{}", i)
)

()

for i in (0..5).step_by(2) {
    println!("{}", i);
}

0
2
4

()

for i in (0..5).rev() {
    println!("{}", i);
}

()

for i in (0..5).rev().step_by(2) {
    println!("{}", i);
}

4
2
0

()

(1..10).map(|x| x + 1).collect::<Vec<_>>()

[2, 3, 4, 5, 6, 7, 8, 9, 10]

(1..10).filter(|x| x % 3 == 0).collect::<Vec<_>>()

[3, 6, 9]

(1..10).filter(|x| x % 3 == 0).next()

Some(3)

let x = (1..10).filter(|x| x % 3 == 0).next().unwrap();
x

3

(1..10).filter(|x| x % 2 == 0).count()

4

(1..10).max()

Some(9)

(1..10).iter().sum()

(1..10).iter().sum()
        ^^^^ method not found in `std::ops::Range<{integer}>`
no method named `iter` found for struct `std::ops::Range<{integer}>` in the current scope

let v = vec![1, 2, 3];
v

[1, 2, 3]

let s: i32 = v.iter().sum();
s

6

v.iter().sum::<i32>()

6

(v.iter().sum::<i32>() as f64) / 6.0

1.0

v.iter().sum::<i32>() as f64 / 6.0

1.0

References¶

Module std::collections