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

Here is another Linq approach which extracts the first number out of a string.

string input = "123 foo 456";
int result = 0;
bool success = int.TryParse(new string(input
                     .SkipWhile(x => !char.IsDigit(x))
                     .TakeWhile(x => char.IsDigit(x))
                     .ToArray()), out result);

Examples:

string input = "123 foo 456"; // 123
string input = "foo 456";     // 456
string input = "123 foo";     // 123

Answer 2

Did the reverse of one of the answers to this question: How to remove numbers from string using Regex.Replace?

// Pull out only the numbers from the string using LINQ

var numbersFromString = new String(input.Where(x => x >= '0' && x <= '9').ToArray());

var numericVal = Int32.Parse(numbersFromString);

Answer 3

\d+ is the regex for an integer number. So

//System.Text.RegularExpressions.Regex
resultString = Regex.Match(subjectString, @"\d+").Value;

returns a string containing the first occurrence of a number in subjectString.

Int32.Parse(resultString) will then give you the number.

Answer 4

You can also try this

string.Join(null,System.Text.RegularExpressions.Regex.Split(expr, "[^\\d]"));

Answer 5

Just use a RegEx to match the string, then convert:

Match match = Regex.Match(test , @"(\d+)");
if (match.Success) {
   return int.Parse(match.Groups[1].Value);
}

Answer 6

var match=Regex.Match(@"a99b",@"\d+");
if(match.Success)
{
    int val;
    if(int.TryParse(match.Value,out val))
    {
        //val is set
    }
}