Regex to get first number in string with other characters

Question

I\'m new to regular expressions, and was wondering how I could get only the first number in a string like 100 2011-10-20 14:28:55. In this case, I\'d want it to

Answer 1

Try this to match for first number in string (which can be not at the beginning of the string):

    String s = "2011-10-20 525 14:28:55 10";
    Pattern p = Pattern.compile("(^|\\s)([0-9]+)($|\\s)");
    Matcher m = p.matcher(s);
    if (m.find()) {
        System.out.println(m.group(2));
    }

Answer 2

This string extension works perfectly, even when string not starts with number. return 1234 in each case - "1234asdfwewf", "%sdfsr1234" "## # 1234"

    public static string GetFirstNumber(this string source)
    {
        if (string.IsNullOrEmpty(source) == false)
        {
            // take non digits from string start
            string notNumber = new string(source.TakeWhile(c => Char.IsDigit(c) == false).ToArray());

            if (string.IsNullOrEmpty(notNumber) == false)
            {
                //replace non digit chars from string start
                source = source.Replace(notNumber, string.Empty);
            }

            //take digits from string start
            source = new string(source.TakeWhile(char.IsDigit).ToArray());
        }
        return source;
    }

Answer 3

Just

([0-9]+) .* 

If you always have the space after the first number, this will work

Answer 4

Try ^(?'num'[0-9]+).*$ which forces it to start at the beginning, read a number, store it to 'num' and consume the remainder without binding.