Dfyjkt

I am making a simple console program that converts between Celsius and Fahrenheit. The program takes user input multiple times, once for the type of conversion and once for the value to convert. When I run the program it compiles and runs without error, however, it does not actually return any value.

Here is the program:

use std::io;

// C to F: F = C*(9/5) + 32
// F to C: C = (F-32)*(5/9)

/**********Converts between Fahrenheit and Celsius*********/

fn main() -> () 
 println!("Do you want to convert to Celsius or Fahrenheit? Input C or F");
 let mut convert_type = String::new();

 io::stdin()
 .read_line(&mut convert_type)
 .expect("Failed to conversion type.");

 let t = String::from(convert_type);

 println!("You want to convert to: ", t);
 println!("What temperature would you like to convert?");
 let mut temp = String::new();

 io::stdin()
 .read_line(&mut temp)
 .expect("Failed to read temperature.");

 let temp: i32 = match temp.trim().parse() 
 Ok(temp) => temp,
 Err(_e) => -1,
 ;

 if &t == "C" 
 println!("", ctof(temp));
 else if &t == "F" 
 println!("", ftoc(temp));
 


// Celsius to Fahrenheit
fn ctof(c: i32) -> i32 
 (c * (9 / 5)) + 32


//Fahrenheit to Celsius
fn ftoc(f: i32) -> i32 
 (f - 32) * (5 / 9)

Here is a snippet of the console, as you can see it does not output the conversion:

cargo run --verbose
 Compiling ftoc v0.1.0 (/Users/roberthayek/rustprojects/ftoc)
 Running `rustc --crate-name ftoc src/main.rs --color always --crate-type bin --emit=dep-info,link -C debuginfo=2 -C metadata=8f02d379c2e5c97d -C extra-filename=-8f02d379c2e5c97d --out-dir /Users/roberthayek/rustprojects/ftoc/target/debug/deps -C incremental=/Users/roberthayek/rustprojects/ftoc/target/debug/incremental -L dependency=/Users/roberthayek/rustprojects/ftoc/target/debug/deps`
 Finished dev [unoptimized + debuginfo] target(s) in 1.16s
 Running `target/debug/ftoc`
Do you want to convert to Celsius or Fahrenheit? Input C or F
C
You want to convert to: C

What temperature would you like to convert?
0

You should make a habit of handling all cases, even ones you don't expect. If you had done so, you would have found the problem. So instead of this:

if &t == "C" 
 println!("", ctof(temp));
 else if &t == "F" 
 println!("", ftoc(temp));

You could write this (you could also use a final else branch with no if, but match is much more appealing):

match t.as_str() 
 "C" => println!("", ctof(temp)),
 "F" => println!("", ftoc(temp)),
 _ => println!("please enter C or F"),

And when you ran your program, you would see that t seemed to be equal to neither "C" nor "F". That would hopefully lead you to check the value of t, by doing a debug print.

match t.as_str() 
 "C" => println!("", ctof(temp)),
 "F" => println!("", ftoc(temp)),
 _ => println!("t = :?", t),

At which point you would see that the value of t is not "C", but "Cn" or "Crn". And you would then realize that read_line was not stripping the newline from your string for you.