El BrunoHi !
During today’s Rust lession in the “First Steps with Rust” (in Spanish), we reviewed the Hashmaps in Rust. We talk about the behavior when we access a non existing item, and it was nice to get a NONE return instead of an error or an exception.
In example this code:
use std::collections::HashMap;
fn main() {
let mut pets = HashMap::new();
pets.insert("Ace", "dog");
pets.insert("Goku", "car");
pets.insert("Jim", "squirrel");
println!("{:#?}", pets);
let net = "Net";
let net_animal = pets.get(net);
println!("{} is a {:?}", net, net_animal);
}
Returns this output.
warning: `HashMap01` (bin "HashMap01") generated 1 warning
Finished dev [unoptimized + debuginfo] target(s) in 0.83s
Running `target\debug\HashMap01.exe`
{
"Ace": "dog",
"Goku": "car",
"Jim": "squirrel",
}
Net is a None
There is no element with the key “Net”, so it returs None.
Is the same in C# ? 🤔
And, hey, what happens with this in C#? I was sure that, if I try to access a non-existing element, the app will trigger an error. So I tested this code
// create a new dictionary named petsDic
Dictionary<string, string> petsDic = new Dictionary<string, string>();
petsDic.Add("Ace", "dog");
petsDic.Add("Goku", "car");
petsDic.Add("Jim", "squirrel");
// print the petsDic items
foreach (KeyValuePair<string, string> pet in petsDic)
Console.WriteLine(pet.Key + " is a " + pet.Value);
// get an element from the dictionary
var petD = petsDic["Milly"];
Console.WriteLine("Milly is a " + petD);
And, as expected, I got an System.Collections.Generic.KeyNotFoundException !
But hey, for this sample I’m using a Dictionary<>. So let’s give this a try using a Hashtable in C#. So let’s try this code.
using System.Collections;
// create a new hashtable named pets
Hashtable pets = new Hashtable();
pets.Add("Ace", "dog");
pets.Add("Goku", "car");
pets.Add("Jim", "squirrel");
// print the pets hashtable items
foreach (DictionaryEntry pet in pets)
Console.WriteLine(pet.Key + " is a " + pet.Value);
// get an element from the hashtable
var petM = pets["Milly"];
Console.WriteLine("Milly is a " + petM);
And, this scenario didn’t trigger an Exception 👍.
During this Rust series, we talk a lot about understanding how each data type works. And as a plus, I’ll add that if you have some previous knowledge, it’s better to check and validate the knowledge ! I was caught in a false assumption in this one !
Happy coding!
Greetings
El Bruno
More posts in my blog ElBruno.com.
