Why doesn't this print nomatter what I input? [duplicate] - if-statement

Question

This question already has answers here:
Why does my string not match when reading user input from stdin?
(3 answers)
Closed 11 months ago.
I am new to rust and just learned about user input from the command line, I tried making this simple program to test out. When I run it I don't get any errors but even if I put in "mac" or anything else it doesn't print anything. I would like to understand why this happens, if anyone can explain that I would appreciate it a lot.
here is my code:
use std::io::{stdin, stdout, Write};
fn main() {
print!("State your OS: ");
stdout().flush().expect("Flush Failed!");
let mut input_string = String::new();
stdin()
.read_line(&mut input_string)
.ok()
.expect("Failed to read line!");
if input_string == "mac" {
println!("Mac");
} else if input_string == "windows" {
println!("Windows");
} else if input_string == "linux" {
println!("Linux");
}
}

Answer 1

Your input string has a newline character at the end. This is specified in the documentation of read_line().
One possible solution to your problem would be to trim the string. Example:
use std::io::{stdin, stdout, Write};
fn main() {
print!("State your OS: ");
stdout().flush().expect("Flush Failed!");
let mut input_string = String::new();
stdin()
.read_line(&mut input_string)
.ok()
.expect("Failed to read line!");
let s = input_string.trim();
if s == "mac" {
println!("Mac");
} else if s == "windows" {
println!("Windows");
} else if s == "linux" {
println!("Linux");
}
}
There are other possible approaches to this, but I think in almost all cases it's a good practice to trim() the user input. Note that your user could potentially enter " mac", in which case you would probably want to treat the input as "mac" anyway.