Check digits in string.

[Asotop]

Hey!

I'm currently writing a program which converts a number from binary to int. That part is done, but I'm now trying to check wheither the input string only consists of 1 and 0.

This is what I've tried so far, but it doesnt work the way I want.

string binarynumber;
            bool binaryLoop = true;
            Console.Writeline("Please type in a binary number: ");
            binaryNumber = Convert.ToString(Console.ReadLine());
     
            while (binaryLoop)
            {
                try
                {
                    foreach (char digit in binaryNumber)
                    {
                        int digit = Convert.ToInt32(siffer.ToString());
                        if (digit == 1 || digit == 0)
                        {
                            binaryLoop = false;
                        }
                        else
                        {
                            Console.WriteLine("The binary number can only be 1 and 0, please retype");
                                  
                        }

                    }
                }
                catch(FormatException)
                {
                    Console.WriteLine("The binary number can only be 1 and 0, please retype");;
                }
            }

Any hint? Or better methods?

Regards Asotop.

[arunkumars]

hi, check this, just changed your code.

string binarynumber;
                bool binaryLoop = true;
                Console.WriteLine("Please type in a binary number: ");
                binarynumber = Convert.ToString(Console.ReadLine());
     
                while (binaryLoop)
                {
                    try
                    {
                        foreach (char digit in binarynumber)
                        {
                            //int digit = Convert.ToInt32(siffer.ToString());
                            if (digit == '1' || digit == '0')
                            {
                                binaryLoop = false;
                            }
                            else
                            {
                                //Console.WriteLine("The binary number can only be 1 and 0, please retype");
                                throw new FormatException();
     
                            }
     
                        }
                        Console.WriteLine("works fine");
                        Console.ReadLine();
                    }
                    catch(FormatException)
                    {
                        Console.WriteLine("The binary number can only be 1 and 0, please retype");
                        Console.ReadLine();
                    }
                }

[Momerath]

Put a break after line 15, there is no need to continue checking if the rest of the digits are 0 or 1 after you've found one that fails.

You could also use a Regex

if (Regex.Match(binarynumber, "^[01]+$") == null) {
    // not a binary number
} else {
    // is a binary number
}

[Mitja Bonca]

Or a bit more suphisitcated, using checking if char is number (and a bit different checking of binary data):

bool bExit = false;
  Console.WriteLine("Please type in a binary number: ");
  string binarynumber = Convert.ToString(Console.ReadLine());
  while (!bExit)
  {
      foreach (char digit in binaryNumber)
      {
          if(char.IsDigit(digit)
          {
              int digit = Convert.ToInt32(new string();
              if (digit != '1' || digit != '0')
              {
                   Console.WriteLine("The binary number can only be 1 and 0, please retype");   
                   bExit = true; //char is not 0 or 1
                   break;
              }
          } 
          else 
               bExit = true; // char is not a number!
      }
      break; // all ok!
   }  
   if(!bExit)
   {
       // when code exits the loop, you can continue working, it will 
   }

[Asotop]

Thanks alot, still learning about the different possibilities with Regex, I'll look into each solution.

[Asotop]

@arunkumars

It's almost working now, but if i type in, lets say 10201, it will still go through.

Maybe I shouldent use a foreach loop at all? I won't use the Regex, cause my teacher doesn't approve of it, he prefers doing it the hard way :P

[Mitja Bonca]

Check this out:

bool bExit = false;
            bool bReType = false;
            Console.WriteLine("Please type in a binary number: ");
            while (!bExit)
            {
                while (!bReType)
                {
                    string binarynumber = Convert.ToString(Console.ReadLine());
                    foreach (char digit in binarynumber.ToCharArray())
                    {
                        if (char.IsDigit(digit))
                        {
                            int myInt = int.Parse(digit.ToString());
                            if (myInt != 1 && myInt != 0)
                            {
                                Console.WriteLine("The binary number can only be 1 and 0, please re-type");
                                bReType = true;
                                break;
                            }
                        }
                        else
                        {
                            Console.WriteLine("The char is not a number, please re-type.");
                            bReType = true;
                            break;
                        }
                    }
                    if (!bReType)
                    {
                        bReType = true;
                        bExit = true;
                    }
                }
                bReType = false;
            }
            // when code exits the loop, you can continue working, it will

[Asotop]

Thanks alot.

[arunkumars]

@Asotop,
its working fine for me, i tested n then pasted that code, may be u can paste the code that u have included, i can check.
if my ans helped u, kindly click on the reputation points..
bye.