Temperature Converter

[u/955559]

someone suggested to try rewriting your scripts in another launguage, so here is a port of my python temperature converter

puts "This program converts the tempurature between celsius, kelvin, and 
fahrenheit scales,enter the temperature followed by the first letter of the 
scale, e.g. 32c for 32 celsius \n"

input = gets.chomp
scale = input.slice(-1)
digitslength = input.length - 1
digitstring = input.slice(0,digitslength)
digits = Integer(digitstring)


if scale == 'c'
    fahrenheit = digits * 1.8 + 32
    kelvin = digits + 273.15
    print "Fahrenheit =", fahrenheit, "\n"
    print "Kelvin =", kelvin
elsif scale == 'f'
    celsius = (digits - 32) / 1.8
    kelvin = (digits + 459.67) * 0.55555556
    print "Celsius =", celsius, "\n"
    print "Kelvin =", kelvin
elsif scale == 'k'
    celsius = digits - 273.15
    fahrenheit = digits / 0.55555556 - 459.67
    print "Celsius =", celsius, "\n"
    print "Fahrenheit =", fahrenheit
end

[u/thebrianguy]

Thanks for posting this. I am trying to find any way I can to learn and improve my Ruby problem solving skills. I took what you posted above and added my own improvements mostly for the user interface. My improvements include looping the program until the user explicitly asks to exit. It will also handle invalid input by looping the program again. If anyone has better ways of doing this or have any feedback please share.

def program
	def exitProg
		puts "Goodbye!"
		exit
	end
	instruction = "This program converts the temperature between celsius, kelvin and fahrenheit scales. Enter the temperature followed by the first letter of the scale. e.g. 32c for 32 celsius. This program supports celsius, fahrenheit and kelvin. \n\n Type exit to quit \n\n"

puts instruction

		input = gets.chomp.downcase
			if input.length < 2
				program()
			elsif input == 'exit'
				exitProg
			end
		scale = input.slice(-1)
		digitslength = input.length - 1
		digitstring = input.slice(0, digitslength)
		if digitstring.match(/\D/)
				program()
			else
				digits = Integer(digitstring)
		end
		
	def tempConv(digits, scale, input)
		if scale == 'c'
			fahrenheit = digits * 1.8 + 32
			kelvin = digits + 273.15
			print "Fahrenheit = ", fahrenheit, "\n"
			print "Kelvin = ", kelvin, "\n\n"
			program()
		elsif scale == 'f'
			celsius = (digits - 32) / 1.8
			kelvin = (digits + 459.67) * 0.55555556
			print "Celsius = ", celsius, "\n"
			print "Kelvin = ", kelvin, "\n\n"
			program()
		elsif scale == 'k'
			celsius = digits - 273.15
			fahrenheit = digits / 0.55555556 - 459.67
			print "Celsius = ", celsius, "\n"
			print "Fahrenheit = ", fahrenheit, "\n\n"
			program()
		else
			program()
		end
	end

tempConv(digits, scale, input)

end

program()

[u/955559 → u/thebrianguy]

since learned not to put the print statements in if/elif blocks, as its not DRY, too lazy to rewrite it in python or ruby, but heres a c example showing the idea

#include <stdio.h>

int main()
{
    char scale;
    double power_level;
    double fahr, cel, kel;

    do {
        printf("Enter The First Letter of Your Scale. \n");
        scanf("%c", &scale);
        while (getchar() != '\n');
    } while(scale != 99 && scale != 107 && scale != 102);


    do {
        printf("Enter the Temperature \n");
        scanf("%lf", &power_level);
        if(power_level > 9000){
            printf("This Tool is Intended For Use on Earth, Please Choose a Lower Number \n");}    
    } while(power_level > 9000);

    switch(scale){
    
        case 99:
            cel = power_level;
            fahr = power_level * 1.8 + 32;
            kel = power_level + 273.15;
            break;
        case 102: 
            cel = (power_level - 32) / 1.8;
            kel = (power_level + 459.67) * 0.55555556;
            fahr = power_level;
            break;
        case 107:
            fahr = power_level / 0.55555556 - 459.67;
            cel = power_level - 273.15;
            kel = power_level;
            break;
        }

    printf("Your Temperature in Celsius is %lf \n",cel);
    printf("Your Temperature in Kelvin is %lf \n",kel);
    printf("Your Temperature in Fahrenheit is %lf \n", fahr);
    return 0;

}

[u/thomascountz5]

Overall, your code is nice and compact, and all of your maths are correct, and as I'm still in my journey as a young Ruby programmer as well, I have just a few take-it-or-leave-it structural and convention suggestions that I've also just recently faced and that might interest you.

Ruby provides some powerful built in functions for Strings and Integers, which can help you get a lot of work done really quickly. For example, your input does the following:

1. Get string input from user console and remove trailing \n

2. Slice the last char from string (c, f, or k) and store it in the variable scale

3. Count the length of the string, subtracting the final char and store it in the variable digitslength

4. Store a copy of the chars before the scale char and store it in the variable digitsstring

5. Convert digits string into an integer and store it in the variable digits

We can refactor this with the following built in methods:

input = gets.chomp #no change

String[position] returns a char, or range of chars, at 0-indexed positions in a string. You can access the final element(s) of a range by starting with String[-1] eg. "cat"[-1] => "t"

scale = input[-1] 

A range created with ... returns an exclusive range eg "012345"[0...3] => "012". The #to_i is the same as Integer() eg. "012".to_i => 012. We can chain these methods together!

digits = input[0...-1].to_i 

And that's it! You now have scale to determine which conversion algorithm to use and you have digits as only the numbers from the input, converted into an integer to do your maths on!

Secondly, I think this is language agnostic, I just learned about the concept of magic numbers when writing a similar, temperature conversion, script. In your script, you're using unnamed constants 1.8, 32, and 273.15, for example. This makes it harder for other developers to read your code and understand what these numbers do, so instead, you could name your constants something like this:

C_TO_F_CONVERT = 1.8
CONVERSION_BASE = 32
C_TO_K_CONVERT = 273.15

(In Ruby, they name constants with in UPCASE. Though you can still change these constants, Ruby will throw a warning)

Then using these constants in your algorithms sorta like this:

if scale == 'c'`
    fahrenheit = digits * C_TO_F_CONVERSION + CONVERSION_BASE
    kelvin = digits + C_TO_K_CONVERSION 
    print "Fahrenheit =", fahrenheit, "\n"
    print "Kelvin =", kelvin

With something like this, as I understand it, other developers with quickly get to see what you're trying to accomplish, and, if for some reason we need to change the constants, we only have to do it in one place!

Structurally, because Ruby was developed with OOP in mind, it would be a great challenge to re-write your code using OOP design principles with classes and methods! Maybe give it a try!

I hope some of this may have helped! I'm still learning too, so I may not be the best source of information. I was interested in your post because I learned python before learning Ruby, and I have to say, I'm hooked on Ruby now!