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Daniel Nill

A Coder.


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A Quick Rust tip (Comparing Strings)

I’ve been learning rust recently and so wanted to start tracking things that I’ve learned.

You can learn a lot more about strings in rust via this explainer but one thing I got hung up on was comparing strings.

There are two types of strings in rust, &str and String. It seems that rust is pretty good about deciding which type you want a "some string" to be, but I was having trouble doing something like this:

    let mut guess = String::new();

    io::stdin().read_line(&mut guess).expect("Failed to read line");
    
    if guess == "Q" {
        println!("Goodbye");
        break;
    }

I was worried that while guess was a String "Q" was a &str. Turns out the issue was with the way the read_line formats the string when reading it. By default there is a newline character at the end of the string so you need to use trim().

    let mut guess = String::new();

    io::stdin().read_line(&mut guess).expect("Failed to read line");
    
    if guess.trim() == "Q" {
        println!("Goodbye");
        break;
    }