Bool and char

Store logic and characters with bool and char types.

Bool and char

bool takes the values true/false. A char is written with single quotes and is a 4-byte Unicode scalar value; not just ASCII but Turkish letters and emoji are a single char too:

let aktif = true;
let harf = 'ş';
let emoji = '🦀';
println!("{} {} {}", aktif, harf.is_alphabetic(), emoji);

Double quotes ("a") make a string, single quotes ('a') a char.

char methods

char offers classification and conversion methods:

let c = '7';
println!("{}", c.is_ascii_digit());     // true
println!("{:?}", c.to_digit(10));       // Some(7)
println!("{}", 'a'.to_ascii_uppercase()); // A
println!("{}", 'A' as u32);            // 65

Logical operators short-circuit: in a && b, if a is false, b is never evaluated.

Exercise Digit sum

Walk every character of the text "4096" with .chars(), convert each with to_digit(10) and sum them. Print the sum.

Show example solution

fn main() {
    let mut toplam = 0;
    for c in "4096".chars() {
        toplam += c.to_digit(10).unwrap();
    }
    println!("{}", toplam);
}

Test yourself

What does <code>std::mem::size_of::<char>()</code> return?
- 1
- 2
- 8
- 4
Show answer

4 — A char is 4 bytes so it can hold any Unicode character; inside a string, characters take 1-4 bytes as UTF-8.

Convert to a digit

let d = '9'.____(10);  // Some(9)

Show answer

let d = '9'.to_digit(10);  // Some(9)

Expression and result

'A' as u32

65
'ş'.is_alphabetic()

true
'x'.to_digit(10)

None
!true

false

Next lesson: Tuple

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