C# Convert Alphanumeric phone number

Question

I've been working on this issue for awhile and I've been stuck so I hope someone can push me in the right direction. I have a c# console application that will take in a string and verify that it contains only 0-9, a-z, A-Z, and -.

My issue that I'm having is that I need to convert any letters in the phone number to their respective number. So if I input 1800-Flowers, it will output as 1800-3569377. I have my methods defined:

I'm not looking for the solutions here (this is homework), but I'm looking for a push in the right direction. Do I need to convert the string to a char array to break up each individual character, and then use that in the convert method to switch any letter into a number?

Answer 1

There are certainly a lot of solutions here. Since you're already using Regex, you could approach it in a basic way:

num = Regex.Replace(num, @"[abcABC]", "2");
num = Regex.Replace(num, @"[defDEF]", "3");
//....

or you could create a Dictionary<string,char> and run through each char and convert it to the mapped character. Something like :

var dict = new Dictionary<string, char>(); 
dict.Add("abcABC",'2');
//...

foreach(char c in num.Where(char.IsLetter))
{
    var digit = dict.First(d => d.Key.Contains(c)).Value;
    num = num.Replace(c, digit);
} 

Like you said, the LINQ here is splitting the string to a char array, and looping through ones that are letters

Answer 2

Since this is for school, i'm sure you can't go crazy with more advanced topics. Lets keep it simple with a switch/case.

You can map the letters to their corresponding number first, just use a switch/case to find the correct number depending on the letter.

For example:

String phoneNumber = "1800ab";

for(int x=0; x < phoneNumber.Length; x++)
{
   if(Char.IsLetter(phoneNumber[x]))
   {
      switch(phoneNumber[x].ToString().ToLower())
      {
         case "a":
         case "b":
         case "c":
           //This is number 2!
         break;


      }
   }
}

Answer 3

String already implements IEnumerable<char> - so no need to "break up" there.

Mapping of something to something (like letter code to matching number) is generally done with map (associative array) types (in C#/.Net it is Dictionary) that provide mapping one value ("key") to corresponding "value" - consider using that.

Answer 4

string letter1 = AskuserforInput("first letter");
string number1 = SwitchMethod(letter1);

string letter2 = AskuserforInput("second letter");
string number2 = SwitchMethod(letter2);

string letter3 = AskuserforInput("third letter");
string number3 = SwitchMethod(letter3);

string letter4 = AskuserforInput("fouth letter");
string number4 = SwitchMethod(letter4);

string letter5 = AskuserforInput("fifth letter");
string number5 = SwitchMethod(letter5);

string letter6 = AskuserforInput("sixth letter");
string number6 = SwitchMethod(letter6);

string letter7 = AskuserforInput("seventh letter");
string number7 = SwitchMethod(letter7);

string letter8 = AskuserforInput("eigth letter");
string number8 = SwitchMethod(letter8);

string letter9 = AskuserforInput("ninth letter");
string number9 = SwitchMethod(letter9);

string letter10 = AskuserforInput("tenth letter");
string number10 = SwitchMethod(letter10);
//declaring strings





Console.WriteLine("This is the original letter phone digits");
Console.WriteLine("({0}{1}{2})) {3}{4}{5} - {6}{7}{8}{9} ", letter1,letter2, letter3, letter4, letter5, letter6, letter7, letter8, letter9, letter10);//continue this


    Console.WriteLine("The actual numbers" );
    Console.WriteLine("({0}{1}{2})) {3}{4}{5} - {6}{7}{8}{9} ", number1, number2, number3, number4, number5, number6, number7, number8, number9, number10);//continue this
    Console.Read();

    #region End Program
    //wait for program to acknowledge results
    Console.BackgroundColor = ConsoleColor.White;
    Console.ForegroundColor = ConsoleColor.Red;
    Console.WriteLine("\n\nPlease hit ENTER to end program. . .");
    Console.Read();
    #endregion
    Console.Read();
    //also pulled this back up from a previous program


}

public static string SwitchMethod(string x)
{
    string y = "*";
    switch (x)
    {
        case "0":
            y = "0";
            break;
        case "1":
            y = "1";
            break;
        case "A":
        case "a":
        case "B":
        case "b":
        case "C":
        case "c":
        case "2":
            y = "2";
            break;

        case "D":
        case "d":
        case "E":
        case "e":
        case "F":
        case "f":
        case "3":
            y = "3";
            break;

        case "G":
        case "g":
        case "H":
        case "h":
        case "I":
        case "i":
        case "4":
            y = "4";
            break;

        case "J":
        case "j":
        case "K":
        case "k":
        case "L":
        case "l":
        case "5":
           y = "5";
            break;

        case "M":
        case "m":
        case "N":
        case "n":
        case "O":
        case "o":
        case "6":
            y = "6";
            break;

        case "P":
        case "p":
        case "Q":
        case "q":
        case "R":
        case "r":
        case "S":
        case "s":
        case "7":
            y = "7";
            break;


        case "T":
        case "t":
        case "U":
        case "u":
        case "V":
        case "v":
        case "8":
            y = "8";
            break;

        case "W":
        case "w":
        case "X":
        case "x":
        case "Y":
        case "y":
        case "Z":
        case "z":
        case "9":
            y ="9";
            break;
        default:
            Console.WriteLine("knucklehead, not a letter");
            Console.WriteLine("an '*' will show up");
            break;
            //used cases, next will use to.lower
            //Lynch helped

    }
    return y;


}


public static string AskuserforInput(string x)
{
    Console.WriteLine("\nPlease type {0}", x);
    String input = Console.ReadLine();
    return input;
}

Answer 5

I'm sure someone can think of a better way, but you could loop through each digit and pass it to this function:

int Asc(char ch)
{    
//Return the character value of the given character    
  return (int)Encoding.ASCII.GetBytes(ch)[0];
}

Then just assign a number based on which ASCII character is returned.