C# Parse float from not-only-numerical string [duplicate]

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...

Answer 1

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

Answer 2

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

Answer 3

you can use below regex -

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

Answer 4

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