c# making a loop with a sentinel and show only the letters

Hi, this i'm trying to make a loop that would read a list of character (including numbers) that you type in terminated by a period and that would only write the letters and ignore the other characters. How would i do this?? Thats the code ive been doing but there seem to be a problem with != operator saying it can't work with a string or int. Anybody know how i could make this work?? Ive search in many places and i can't find an answer.

Code:

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using System;
class text
{
    static void Main()
    {
        Console.WriteLine("Enter text");
        string line = Console.In.ReadLine();
        int text = Convert.ToInt32(line);
        int sum = 0;
        int i = 0;
        while (text != -9)
        {
            sum = sum + text;
            i++;
            line = Console.In.ReadLine();
            text = Convert.ToInt32(line);
        }
        Console.Write("The letters are {0}", sum);
        Console.In.Read();
        return;
    }
}

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This code will only give:
Enter text
9949449
-9
The letters are 9949449

Is there a way i can make the sentinel finish the loop on the same line and use another character like a period. Also is there a way to make it read other values than numbers, the string would logicly work but the != doesn't accept it. And if i enter letters it crashes.

345u435hu43i$$$@@@.
The letters are uhui

Have you ever dealt with regular expressions? Google it and you should be able to find a regular expressions that will allow you to extract text only and use the C# support for Regex....

Regular Expressions Usage in C#

Not got my compiler ATM...

You can use the C# Char structure methods.

Code:

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Console.WriteLine("Enter text");
string line = Console.In.ReadLine();
int Length = line.Length;

for(int i=0;i<Length;i++)//check each character
{
      if(line[i] == '.') //look for a period to exit
          //exit
    else if(Char.IsDigit(line[i]))//is a number
        //process input
    else
        //handle bad input 
}

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Quote:

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Originally Posted by novacain

Not got my compiler ATM...

You can use the C# Char structure methods.

Code:

---

Console.WriteLine("Enter text");
string line = Console.In.ReadLine();
int Length = line.Length;

for(int i=0;i<Length;i++)//check each character
{
      if(line[i] == '.') //look for a period to exit
          //exit
    else if(Char.IsDigit(line[i]))//is a number
        //process input
    else
        //handle bad input 
}

---

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ha i haven't thought about that thank you.

LINQ could be useful too:

Code:

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foreach(char ch in line.Where((c) => Char.IsLetter(c)))
  Console.Write(ch);

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