public/subjects/string_literals

string literals

Instructions

Create the following functions:

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

This exercise will test how many times the heap is going to be allocated!
So try your best to allocate the minimum data on the heap!

Notions

• https://doc.rust-lang.org/1.22.0/book/first-edition/the-stack-and-the-heap.html
• https://doc.rust-lang.org/rust-by-example/primitives/literals.html

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 {
}

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

student@ubuntu:~/string_literals/test$ cargo run
true
true
true
("ru", "st")
1
student@ubuntu:~/string_literals/test$