Find and extract a number from a string

Question

I have a requirement to find and extract a number contained within a string.

For example, from these strings:

string test = \"1 test\"
string test1 =         


        

Answer 1

static string GetdigitFromString(string str)
    {
        char[] refArray = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
        char[] inputArray = str.ToCharArray();
        string ext = string.Empty;
        foreach (char item in inputArray)
        {
            if (refArray.Contains(item))
            {
                ext += item.ToString();
            }
        }
        return ext;
    }