How would I write the Regex for this?

Question

If I have this string:

18.62 PURCHASE REF 1 829400493183

All I want to pull out is the 18.62 . How would I do that without getting the rest of the string? (For instance, without getting the 829400493183 .

If it would be easier to do this without using regex I am open to suggestion as well.

Marked as C# also because this is going into an application I am working on.

Answer 1

It could be done without RegEx, assuming that 18.62 is separated by a space from the rest:

string s = "18.62 PURCHASE REF 1 829400493183";
string r = s.Split()[0];

Answer 2

Here's a different solution, as you don't really need Split for this:

var str = "18.62 PURCHASE REF 1 829400493183";
var value = str.Substring(0, str.IndexOf(' '));

By the way, the Regex solution would look something like this:

var str = "18.62 PURCHASE REF 1 829400493183";
var value = Regex.Match(str, @"^-?[0-9]+(?:\.[0-9]+)").Value;

This validates the number but is still overkill as a simple int.TryParse will do the job.

You just need to add error checks ( IndexOf returning -1, Match returning null ).

Answer 3

Seems like op wants the first number rather than first word. If yes then use the below regex and get the first number from group index 1.

Regex rgx = new Regex(@"^\D*(\d+(?:\.\d+)?)");

DEMO