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

var outputString = String.Join("", inputString.Where(Char.IsDigit));

Get all numbers in the string. So if you use for examaple '1 plus 2' it will get '12'.