string replacing - C#

Well, you will get about 874355876234857 answers with String.Replace and Regex.Replace, so here's a LINQ solution:

code = new String((from c in code where Char.IsDigit(c) select c).ToArray());

Or using extension methods:

code = new String(code.Where(c => Char.IsDigit(c)).ToArray());

The best way would be to user Regular Expressions. You example would be:

RegEx.Replace("23232-2222-d23231", "\\D+", "");

Yes you can use String.replace but it would be wiser to use regex so that you can match a lot more criteria with a lot less effort.

Regular expressions, as sampled, are the simplest and shortest.

I wonder if below would be faster?

            string sample = "23232-2222-d23231";
            StringBuilder resultBuilder = new StringBuilder(sample.Length);
            char c;
            for (int i = 0; i < sample.Length; i++)
            {
                c = sample[i];
                if (c >= '0' && c <= '9')
                {
                    resultBuilder.Append(c);
                }
            }
            Console.WriteLine(resultBuilder.ToString());
            Console.ReadLine();

guessing it would depend on a few things, including string length.

The simplest would be to use Replace.

 string test = "23232-2222-d23231";
 string newString = test.Replace("-","").Replace("d","");

But using REGEX would be better, but tougher.

It is not (easily) possible with string.Replace(). The simplest solution is the following function/code:

public string GetDigits(string input)
{
    Regex r = new Regex("[^0-9]+");
    return r.Replace(input, "");
}

I would use a regular expression.

See this post Regex for numbers only

You can use a simple extension method:

    public static string OnlyDigits(this string s)
    {
        if (s == null)
            throw new ArgumentNullException("null string");

        StringBuilder sb = new StringBuilder(s.Length);
        foreach (var c in s)
        {
            if (char.IsDigit(c))
                sb.Append(c);
        }
        return sb.ToString();
    }

Try

string str="23232-2222-d23231";
str=Regex.Replace(str, @"\D+", String.Empty);

You could use LINQ:

string allDigits = new String(input.Where(c => Char.IsDigit(c)).ToArray());

You can use a regular expression.

string str = "sdfsdf99393sdfsd";
str = Regex.Replace(str, @"[a-zA-Z _\-]", "");

I've used this to return only numbers in a string before.