Convert a Letter to its alphabet numerical Rank

Question

I am trying to convert a letter to its alphabet numerical order for example if I have an 'A' it will give me 00 or a 'C' 02

How can I code this in c# ?

EDIT : This is what I tried

I created this class :

   public class AlphabetLetter 
    {
        public char Letter {get; set;}
        public int Rank {get; set;} 
    }

Those Two Lists :

     public List<char> Letters = new List<char> {
  'a' ,'b' ,'c' ,'d' ,'e', 'f' ,'g' , 'h' ,  'i' , 'j' , 'k' , 'l' , 'm',
  'n' ,'o' ,'p' , 'q' , 'r' , 's' , 't' , 'u' , 'v' , 'w' , 'x' , 'y' , 'z'     
    };
        public List<int> Ranks = new List<int> { 

        00,01,02,04,05,06,07,08,09,10,11,12,13,
        14,15,16,17,18,19,20,21,22,23,24,25

        };


    public List<AlphabetLetter> Alphabet = new List<AlphabetLetter>( );

I created the Alphabet in my Constructor :

for (int i = 0; i < 25; i++) 
           {
               Alphabet.Add(new AlphabetLetter { Rank = Ranks[i], Letter = Letters[i] });

And tried to match a char with this function :

   public  int   Numberize(char Letter)
       {

           if (Letter != null)
           {
               foreach (AlphabetLetter _letter in Alphabet)
               {

                   if (Letter == _letter.Letter)
                   {

                       return _letter.Rank;

                   }
                   else
                   {
                       return 896;
                   }
               }
           }
           else {

               return 999;
           }



       }
               }

But this method is not working and is too tedious.

Any suggestions?

By busting out your friendly IDE and writing some code yourself. Try that. Then if you have issues come ask a question. — eddie_cat, Jun 19 '14 at 19:01
Yes i have already tried some code but it is not working i will post it on an edit — user2505650, Jun 19 '14 at 19:03
Granted, this is pretty basic. That being said, not every new programmer (especially if they didn't go to school) is going to recognize that characters are just numbers in a table. — BradleyDotNET, Jun 19 '14 at 19:07
I didn't say that because it's basic; I said it because it's so basic that Googling it and trying something would have taken less time than asking a question here. http://stackoverflow.com/questions/20044730/convert-character-to-its-alphabet-integer-position — eddie_cat, Jun 19 '14 at 19:11
That code has to got to be the most convoluted way I have ever seen to try and solve this problem. Just take advantage of the ASCII table as in the answers :) — BradleyDotNET, Jun 19 '14 at 19:15
Though I haven't looked at it close enough, it looks like your code should work if you just remove the `else { return 896; }`. — ispiro, Jun 19 '14 at 19:18
Still after I remove the else {return 896; } I have the error that function does not always return a result how can I fix this? — user2505650, Jun 19 '14 at 19:24
@user2505650 Put it right after the closing bracket that's after it = after the `foreach`'s closing bracket. — ispiro, Jun 19 '14 at 19:26
By the way - Your method, though not optimal in other ways, has the advantage of not being dependent on the characters being stored in sequence. This is probably inconsequential, but is a good programing habit - not to just assume things! — ispiro, Jun 19 '14 at 19:29
@user2505650 OK. So I tested now - You have to just `return 896;` after the `foreach`'s closing bracket. Without the `else { }`. And the input should be a lowercase letter only. Tested. Works. You also have to add a `03` in `Ranks`. And change the `25` in the initialization to `26`. — ispiro, Jun 19 '14 at 19:34
i am sorry i tried to add the return after the foreach but i still have the same error can you please paste your version ? — user2505650, Jun 19 '14 at 19:46

BradleyDotNET · Accepted Answer · 2014-06-19T19:20:48.747

4

You start by simply getting its Unicode value:

int charValue = Convert.ToInt32('A');

Then account for where 'A' is on the Unicode table (65)

int rank = charValue - 65;

Note that this won't work for lower case letters, as they are in a different position. You could use ToLower or ToUpper on the string version of the character to nullify this (as in the other answer).

edited Jun 19 '14 at 19:20

answered Jun 19 '14 at 19:02

BradleyDotNET

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i would like to code it myself without using any such libraries – user2505650 Jun 19 '14 at 19:08
1

@user2505650, by "libraries" do you mean the `Convert` class? Its basically just doing a cast. If you cant cast, then I'm not sure what you are going to do... – BradleyDotNET Jun 19 '14 at 19:10
@user2505650 Would (int)'A' be any better? That is basically what it is doing... You can go look up the source for Convert on line to see exactly what it does. C# has great libraries for hiding that detail from you, why the restriction? – BradleyDotNET Jun 19 '14 at 19:19
Note that originally I said ASCII. Convert.ToInt32 takes a *unicode* character. The position of "A" is the same in both however. – BradleyDotNET Jun 19 '14 at 19:22
I try by curiosity to see how much I can code without using any libraries – user2505650 Jun 19 '14 at 19:25
@user2505650, but casting isn't using a library. Its just a language feature. I abstracted that cast (or whatever it actually does) through a convenient (and more readable) function call. Is casting really a problem? – BradleyDotNET Jun 19 '14 at 19:27

ispiro · Answer 2 · 2014-06-19T19:09:30.577

2

string yourLetter = "C";
int i = yourLetter.ToLower().ToCharArray()[0] - 'a';

This returns 2.

An explanation: The characters as char's are in sequential order. However, there are two sequences - of uppercase, and of lowercase. So first we convert it to lowercase.

Then change it to a character (by using the built in method for turning a string into a character array, and then taking the first and only one).

Then, using the fact that c# will happily treat the char as a number, subtract the first of the sequence from it.

edited Jun 19 '14 at 19:09

answered Jun 19 '14 at 19:02

ispiro

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Someone has downvoted every answer. I guess because they don't like the question? The only problem I have with your answer is that it lacks an explanation. Not worth a downvote though. – BradleyDotNET Jun 19 '14 at 19:05
Good explanation! I gave you my +1 for a case-insensitive solution. – BradleyDotNET Jun 19 '14 at 19:12

merlin2011 · Answer 3 · 2014-06-19T19:12:01.807

0

You do not need any fancy conversion. Just subtract ascii A and add 1.

using System;
using System.IO;

public class P{
    public static void Main(string[] args) {
       var letter = 'C';
       Console.WriteLine(letter - 'A' + 1);
    }
}

If you want to pad with leading zeroes, use ToString with a format.

   Console.WriteLine((letter - 'A' + 1).ToString("00"));

edited Jun 19 '14 at 19:12

answered Jun 19 '14 at 19:06

merlin2011

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Convert a Letter to its alphabet numerical Rank

3 Answers3