chars and bytes

Split a string into chars or bytes iterators.

chars and bytes

Rust stores text as UTF-8. Turkish letters (ç, ğ, ı, ö, ş, ü) take two bytes. That's why len() gives the byte count and chars().count() the character count:

let s = "çay";
println!("{} {}", s.len(), s.chars().count());   // 4 3
for b in s.bytes() { print!("{b} "); }           // 195 167 97 121

Use chars() to process text character by character; the byte level is only for binary protocols and ASCII work.

The char type

char is a 4-byte Unicode scalar value, written in single quotes. It has handy methods:

let c = 'ğ';
println!("{}", c.is_alphabetic());          // true
println!("{}", '7'.to_digit(10).unwrap());  // 7
println!("{}", 'a'.to_ascii_uppercase());   // A
let ters: String = "abc".chars().rev().collect();   // "cba"

to_uppercase() returns an iterator, not a single char, because the uppercase form of some letters is more than one character (ß → SS).

Exercise Letters and bytes

For let s = "Ağaç";, print the byte count, the character count and the characters reversed (chars().rev().collect::<String>()) on one line.

Show example solution

fn main() {
    let s = "Ağaç";
    let ters: String = s.chars().rev().collect();
    println!("{} {} {}", s.len(), s.chars().count(), ters);
}

Test yourself

What is <code>"şeker".len()</code>?
- 5
- 10
- 4
- 6
Show answer

6 — "ş" is two bytes, the remaining four letters one byte each: 2 + 4 = 6.

Count characters

let s = "çay";
let n = s.____().count();   // 3

Show answer

let s = "çay";
let n = s.chars().count();   // 3

Expression and result

"çay".len()

4
"çay".chars().count()

3
'ğ'.is_alphabetic()

true
"abc".chars().rev()

"cba" (with collect)

Next lesson: Slicing strings

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