Why can't i convert from Fahrenheit to Celsius?

Question

My C# code keeps returnng me a wrong conversion result. As far as i know, the conversion formula is correct, but it keeps displaying wrong results.

e.g: 70°F gives me 12,777777 °C. Can you check my code out ?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Temperature
{
    class Program
    {    
        class Temperature
        {
            public double temp;

            public void Convert(double value)
            {
                double tEmp;
                tEmp = (value - 32) / 1.8;
                Console.WriteLine("The temperature in °C is :" + tEmp);
                Console.ReadKey();
            }
        }

        static void Main(string[] args)
        {
            double f;
            Temperature c = new Temperature();
            f = Console.Read();
            c.Convert(f);
        }
    }
}

@EldarDordzhiev: Just for people that don't do this every day. Like me. — Patrick Hofman, Nov 21 '14 at 14:55
@DavidHeffernan It does. If you try running this program, you will get the described result. However, this problem could be solved by simply setting a breakpoint inside `Convert` and seeing what `value` is. — p.s.w.g, Nov 21 '14 at 15:00
@GrantWinney: It would make the search query for google a much more practical. — Patrick Hofman, Nov 21 '14 at 15:19

score 13 · Answer 1 · edited May 23 '17 at 12:08

13

your problem is

f = Console.Read();

It just reads the first character, not your entire line of input. Try

f = Convert.ToDouble(Console.ReadLine());

Here's a good answer on the difference between Console.Read vs. Console.ReadLine()

edited May 23 '17 at 12:08

Community

1
1

answered Nov 21 '14 at 14:54

Jonesopolis

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Correct, this is the source of the problem, but you should explain *why* `Console.Read` of `70` gives `12.78` instead of `21.11` – p.s.w.g Nov 21 '14 at 14:56
Console.Read returns an Int32 which represents a single character that was read or -1. See http://msdn.microsoft.com/en-us/library/system.console.read – Sam Greenhalgh Nov 21 '14 at 14:58
Thanks. I didin't know about the "Convert.ToDouble" method. – wes Nov 21 '14 at 22:33

score 3 · Accepted Answer · answered Nov 21 '14 at 15:06

Console.Read() returns the ordinal value of the next character in the input stream.

The first character in your input stream is '7' which has an ordinal value of 0x0037. Represented as decimal this is 55 and (55-32)/1.8 is 12.7777.

You should be using Console.ReadLine() rather than Console.Read().

Why can't i convert from Fahrenheit to Celsius?

2 Answers2