C# Parse float from not-only-numerical string

Question

I receive a formatted string and I can't change the source ; it look something like this :

{
"value": 4.12
}

I have to parse it into a double to show only the number. I get I should clean it with a regex before using double.TryParse(), but I have no idea how to format the regex...

if source is a JSON string, deserialize it to obtain property value — hmnzr, May 02 '17 at 14:29
If you want to learn regular expressions, the resources on the internet for doing so would literally reach to the moon and back. — 15ee8f99-57ff-4f92-890c-b56153, May 02 '17 at 14:31
quick and dirty: `double result = double.Parse(Regex.Match(source, @"[0-9]*\.?[0-9]+").Value);` — Dmitry Bychenko, May 02 '17 at 14:31

Leonardo · Answer 1 · 2017-05-02T14:31:18.753

2

if you only missed a double-quotes around the value, that is a valid JSON. You can parse it using almost any json library.

edited May 02 '17 at 14:31

answered May 02 '17 at 14:29

Leonardo

10,737
10
62
155

1

Doesn't look like valid JSON to me, although I didn't downvote you – KSib May 02 '17 at 14:29
1

@KSib i think he missed the double-quotes only... common typo... – Leonardo May 02 '17 at 14:30
1

Looks like you were correct. I upvoted you as well to counter that downvote. Cheers. – KSib May 02 '17 at 15:41

Dmitry Egorov · Answer 2 · 2017-05-02T14:48:28.377

With LINQ to JSON you may retrieve the value in one line:

var json = @"{
    ""value"" : 4.12
}";
var value = (double)JObject.Parse(json)["value"];

Demo: https://dotnetfiddle.net/e0viPY

P.S.

Since Json.NET accepts more relaxed syntax, this code would work even with the original question edition (i.e. unquoted key):

var json = "{ value : 4.12 }";
var value = (double)JObject.Parse(json)["value"];

Demo: https://dotnetfiddle.net/iLERPb

score 0 · Answer 3 · answered May 02 '17 at 14:32

0

you can use below regex -

[0-9]+(.[0-9][0-9]?)?

answered May 02 '17 at 14:32

Ravi Shankar

86
7

score 0 · Answer 4 · answered May 02 '17 at 14:34

Quick and dirty regular expression soluition:

  string source = @"{
     ""value"": 4.12
  }";

  double result = double.Parse(Regex.Match(source, @"-?[0-9]*\.?[0-9]+").Value,
    CultureInfo.InvariantCulture);

A better implementation, however, is to decerialize it as JSON

C# Parse float from not-only-numerical string

4 Answers4