Question

I need a little help for finding regular expression that suits my need, what I want is that may the input be any string, the regular expression finds any and all integer values and returns them, say

string s1 = "This is some string"
string s2 = " this is 2 string"
string s3 = " this is 03 string"
string s4 = "4 this is the 4th string"
string s5 = "some random string: sakdflajdf;la  989230"
string s6 = "3494309 !@# 234234"

Now what I want is for the regular expression to return,

for s1 = return null (// nothing)
s2 = return 2
s3 = return 0 and 3 (// may separately as 0 and 3 or together as 03 doesn't matter)
s4 = return 4 and 4 (// it has 4 2 times right?)
s5 = 989230 (// may together as this or separately as 9 8 9 2 3 0 again is unimportant, but what's important is that it should return all integer values)
s6 = 3494309 and 234234 (// again may they be together as this or like this 3 4 9 4 3 0 9 and 2 3 4 2 3 4 that is unimportant, all that is imp is that it should return all integers)

I have tried [0-9], \d and ^.*[0-9]+.*$, but none of them seemed to work. Can anyone please help?

ps : please see the updated question at Rename file using regular expression

Answer 1

The regular expression that will match one or more numerals in succession is:

\d+

You could apply it this way:

Regex.Matches(myString, @"\d+")

Which will return a collection of MatchCollection object. This will contain the matched values.

You could use it like so:

var matches = Regex.Matches(myString, @"\d+");

if (matches.Count == 0)
  return null;

var nums = new List<int>();
foreach(var match in matches)
{
  nums.Add(int.Parse(match.Value));
}

return nums;