Daily Challenge #1 - String Peeler

Hey, everyone. We've decided to host a daily challenge series. We'll have a variety of challenges, ranging in difficulty and complexity. If you choose to accept the task, your goal is to write the most efficient function you can for your language. Bonus points for any features you add!

I’ll start you off with a simple, straightforward challenge. Our first one comes from user @SteadyX on CodeWars.

Your goal is to create a function that removes the first and last letters of a string. Strings with two characters or less are considered invalid. You can choose to have your function return null or simply ignore.

The fundamentals are important, it only gets more difficult from here.

Happy coding!

---

Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

Want to propose a challenge for a future post? Email [e-mail] with your suggestions!

Comments

[Vladislav Guleaev]

function removeChar(str){
 return str.substr(1, str.length - 2)
};

[Ben Halpern]

Ruby

def remove_first_and_last(string)
  raise "Invalid" if string.size < 3
  string[1..string.size-2]
end

[MetaDave 🇪🇺]

I think you can get away with string[1..-2] there, Ben.

[Ryland G]

JavaScript

(someString) => someString.length > 2 ? someString.slice(1, -1) : undefined;

Python

someString[1:-1] if len(someString) > 2 else None

C++

someString.size() > 2 ? someString.substr(1, someString.size() - 1) : null;

C

int trimString(char someString[])
{
  if (strlen(someString) > 2) {
    char *copy = malloc((strlen(someString) - 2) * sizeof(char));
    memmove (copy, someString + 1, strlen(someString) - 2);
    printf("%s", copy);
    free(copy);
    return 0;
  }
  return 1;
}

[Rafael Acioly]

Let people do something 😂

[Jerome De Leon]

HAHAHA damn. Let me finish my code LOL.

[Vicente G. Reyes]

Python

def remove(yo):
    if yo <= 2:
        print("Not enough characters in string")
    else:
    return yo[1:-1]

[Martin Himmel]

PHP

function remove_string_ends($str) {
    if (strlen($str) <= 2) {
        return null;
    }
    return substr($str, 1, -1);
}

[Claudio Scatoli]

I like that substr trick with the -1, didn't think of that!

How about this one liner?

<?php

function trimThis(string $str)
{
    return (mb_strlen($str) <= 2) ? null : substr($str,1,-1);
}

---

Use mb_string to support multibyte chars, such as Chinese

Also typehinted the argument, you never know...

---

This one is even shorter, possible only if the arg is typehinted tho

<?php
function trimThis(string $str) {
    return substr($str,1,-1) ?: null;
}

When the string is shorter than 2, substr returns false;
when the length is 2, substr returns "".

In both cases it's false, the the return is null.

---

Edit: many typos, I'm on mobile :/

[Corey Alexander]

Ruby

Basic

def remove_first_and_last(some_string)
  raise 'Not long enough' unless some_string.length > 2

  some_string[1..-2]
end

Extra

def remove_first_and_last_n_characters(some_string, chars_to_remove: 1)
  raise 'Not long enough' unless some_string.length > (chars_to_remove * 2)

  start_index = chars_to_remove
  end_index = -1 - chars_to_remove
  some_string[start_index..end_index]
end

[Corey Alexander]

Rust

fn remove_first_and_last(string: &str) -> &str {
    remove_first_and_last_n_chars(&string, 1)
}

fn remove_first_and_last_n_chars(string: &str, chars_to_remove: usize) -> &str {
    if string.len() <= (2 * chars_to_remove) {
        panic!("Input string too short")
    }
    let start = chars_to_remove;
    let end = string.len() - 1 - chars_to_remove;

    &string[start..end]
} 

fn main() {
    println!("Ans: {}", remove_first_and_last("Hello, world!"));
    println!("Ans: {}", remove_first_and_last_n_chars("Hello, world!", 2));
    println!("Ans: {}", remove_first_and_last_n_chars("aa", 1));
    println!("Ans: {}", remove_first_and_last_n_chars("aa", 2));
}

View it in the Rust Playground here: play.rust-lang.org/?version=stable...

[Jordon Replogle]

Perl?

$testing = "Happy coding!";
print &peeler($testing) . "\n";

sub peeler {
    my $str = shift;
    if(length($str) > 2) {
        return substr($str, 1, -1);
    }
}

[E. Choroba]

Or maybe just

sub peeler { shift =~ s/^.|.$//gr }

[Werner Echezuría]

Rust

fn trim_string(string: &str) -> &str {
    if string.len() <= 2 {
        panic!("Input string too short");
    }
    &string[1..string.len() - 1]
}

[Tori Crawford]

Ruby

def remove_char(s)
  raise "invalid string" if s.size < 3

  return s[1..-1].chop
end