Practice - 004

A program to read floating point number and print it in exponent notation

use std::io::{stdin,stdout,Write};

fn main() {
    practice4()
}

fn practice4() {
    let mut s=String::new();
    print!("Please enter some text: ");
    let _=stdout().flush();
    stdin().read_line(&mut s).expect("failed to read from stdin");
    if let Some('\n')=s.chars().next_back() {
        s.pop();
    }
    if let Some('\r')=s.chars().next_back() {
        s.pop();
    }

    println!("You typed: {}",s);

    let trimmed = s.trim();
    let (is_float, float) = match trimmed.parse::<f32>() {
        Ok(f) => (true, f),
        Err(..) => (false, 0.0),
    };

    if !is_float {
        println!("This is not an float: {}", trimmed);
        return;
    }

    println!("Floating point: {}", float);
    println!("Lower Exp: {:e}", float);
    println!("Upper Exp: {:E}", float);
}

Result

Please enter some text: 15
You typed: 15
Floating point: 15
Lower Exp: 1.5e1
Upper Exp: 1.5E1

Please enter some text: 13.0_f32
You typed: 13.0_f32
This is not an float: 13.0_f32