public/subjects/string_literals

string literals

Instructions

Create the following functions:

• is_empty: that returns true if the string is empty.
• is_ascii: that returns true if all characters are within the ASCII range.
• contains: that returns true if the string contains the given pattern.
• split_at: that divides a string in two returning a tuple.
• find: that returns the index of the first character of a given string that matches the pattern.

Expected functions

pub fn is_empty(v: &str) -> bool {
}

pub fn is_ascii(v: &str) -> bool {
}

pub fn contains(v: &str, pat: &str) -> bool {
}

pub fn split_at(v: &str, index: usize) -> (&str, &str) {
}

pub fn find(v: &str, pat: char) -> usize {
}

Your heap allocations will be monitored to ensure that you do not make too many allocations, and that your allocations are reasonably sized.

Usage

Here is a program to test your function

use string_literals::*;

fn main() {
    println!("{}", is_empty(""));
    println!("{}", is_ascii("rust"));
    println!("{}", contains("rust", "ru"));
    println!("{:?}", split_at("rust", 2));
    println!("{}", find("rust", 'u'));
}

And its output

$ cargo run
true
true
true
("ru", "st")
1
$

Notions

• stack and heap
• Literals