Get the first letters of words in a sentence

Question

How I could get the first letters from a sentence; example: "Rust is a fast reliable programming language" should return the output riafrpl.

fn main() {
    let string: &'static str = "Rust is a fast reliable programming language";
    println!("First letters: {}", string);
}

score 9 · Accepted Answer · answered May 14 '18 at 12:24

9

let initials: String = string
    .split(" ")                     // create an iterator, yielding words
    .flat_map(|s| s.chars().nth(0)) // get the first char of each word
    .collect();                     // collect the result into a String

answered May 14 '18 at 12:24

Peter Hall

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3

Why do you not use `split_whitespace()`? – Boiethios May 14 '18 at 12:29
2

@Boiethios Because I didn't think of it! It would also remove the possible panic in ljedrz's answer. – Peter Hall May 14 '18 at 12:40
@PeterHall true, I forgot it accepts multiple whitespaces! – ljedrz May 14 '18 at 12:42
2

I've got to say, using `flat_map` to take advantage of `Option`'s `IntoIterator` functionality is something I never would've considered. – MutantOctopus May 14 '18 at 13:34

ljedrz · Answer 2 · 2018-05-14T14:57:34.590

This is a perfect task for Rust's iterators; here's how I would do it:

fn main() {                                                                 
    let string: &'static str = "Rust is a fast reliable programming language";

    let first_letters = string
        .split_whitespace() // split string into words
        .map(|word| word // map every word with the following:
            .chars() // split it into separate characters
            .next() // pick the first character
            .unwrap() // take the character out of the Option wrap
        )
        .collect::<String>(); // collect the characters into a string

    println!("First letters: {}", first_letters); // First letters: Riafrpl
}

Get the first letters of words in a sentence

2 Answers2