convert string to integer array C#

Question

I'm a C# newbie learning how to work with arrays. I wrote a small console app that converts binary numbers to their decimal equivalents; however, the sytax I've used seems to be causing the app to - at some point - use the unicode designation of integers instead of the true value of the integer itself, so 1 becomes 49, and 0 becomes 48.

How can I write the app differently to avoid this? Thanks

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

namespace Sandbox
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Key in binary number and press Enter to calculate decimal equivalent");
            string inputString = Console.ReadLine();

            ////This is supposed to change the user input into character array  - possible issue here
            char[] digitalState = inputString.ToArray();


            int exponent = 0;
            int numberBase = 2;

            int digitIndex = inputString.Length - 1;
            int decimalValue = 0;
            int intermediateValue = 0;

            //Calculates the decimal value of each binary digit by raising two to the power of the position of the digit. The result is then multiplied by the binary digit (i.e. 1 or 0, the "digitalState") to determine whether the result should be accumulated into the final result for the binary number as a whole ("decimalValue").

            while (digitIndex > 0 || digitIndex == 0)
            {

                intermediateValue = (int)Math.Pow(numberBase, exponent) * digitalState[digitIndex]; //The calculation here gives the wrong result, possibly because of the unicode designation vs. true value issue
                decimalValue = decimalValue + intermediateValue;


                digitIndex--;
                exponent++;


            }

            Console.WriteLine("The decimal equivalent of {0} is {1}", inputString, intermediateValue);
            Console.ReadLine();


        }
    }
}

I know it doesn't really answer your question, but all your code could be reduced to `Convert.ToInt32(inputString, 2)` - see [this question](http://stackoverflow.com/questions/9149728/convert-binary-string-into-integer). — Charles Mager, Sep 13 '15 at 10:52
No worries. I'm trying to work out the syntax of arrays and looping structures; hence the unecessarily clunky code. Your approach is still worth knowing though - thanks. — Zengetsu, Sep 13 '15 at 11:03
It's ironic that the question correctly refers to Unicode while several answers incorrectly refer to ASCII. — Tom Blodget, Sep 13 '15 at 17:14

Hamed · Answer 1 · 2015-09-13T11:01:57.827

1

Simply use the following code

for (int i = 0; i < digitalState.Length; i++)
{
    digitalState[i] = (char)(digitalState[i] - 48);
}

After

char[] digitalState = inputString.ToArray();

Note that the value of a character, for example '1' is different from what it represents. As you already noticed '1' is equal to ASCII code 49. When you subtract 48 from its value (49) it becomes 1.

edited Sep 13 '15 at 11:01

answered Sep 13 '15 at 10:56

Hamed

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Richard Schneider · Answer 2 · 2015-09-13T11:09:06.930

@CharlesMager says it all. However, I assume this is a homework assignment. So as you said multiplying by the ASCII value is wrong. So just subtract '0' (decimal value 48) from ASCII value.

intermediateValue = (int)Math.Pow(numberBase, exponent) 
  * ((int)digitalState[digitIndex] - 48);

You code is ugly, there is no need to go backwards from the string. Also using Math.Power is inefficient, shifting (<<) is equivalent for binary powers.

 long v = 0;
 foreach (var c in inputString)
 {
    v = (v << 1) + ((int)c - 48);
 } 
 Console.WriteLine("The decimal equivalent of {0} is {1}", inputString, v);
 Console.ReadLine();

score 0 · Accepted Answer · edited Sep 15 '15 at 04:33

there were two errors: you missed the "-48" and wrote the intermediate instead of the result (last line). Not sure how to unline some parts in the codeblock ;)

intermediateValue = (int)Math.Pow(numberBase, exponent) * (digitalState[digitIndex]-48; 
//The calculation here gives the wrong result, 
//possibly because of the unicode designation vs. true value issue
decimalValue += intermediateValue;
(.....)
Console.WriteLine("The decimal equivalent of {0} is {1}", inputString, decimalValue);

convert string to integer array C#

3 Answers3