Better way to converting string [123,234,...] to List and back

Question

Basically, I am trying to convert what appears to be an array of integer values stored in a string type.

[123,234,345,456] // example

Currently, I am doing the following to convert string to List<int> or an int[]:

var intList = "[123,234,345,456]".Replace("[","").Replace("]","").Split(new[] {','}, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).Tolist();

Perform required operations (sort, add, remove) on the list and convert it back to a string:

string.Format("[{0}]", string.Join(",", intList));

But then this got me thinking. The data that I am working with looks like JSON. Surely there must a more direct way of converting the string into an array of integers?

I looked at using JArray.Parse(string) from Newtonsoft.Json.Linq but isn't that just adding an extra layer of complexity as now I am dealing with JArray<JToken> instead of standard int[].

If anyone has a neater solution that doesn't involve adding methods, extensions or libraries I would appreciate if you can share your knowledge.

Possible duplicate of [Parsing JSON list to int array in c#](https://stackoverflow.com/questions/49341784/parsing-json-list-to-int-array-in-c-sharp) — kgzdev, Feb 25 '19 at 08:45
If your input really is that simple you could use a regex, but that will soon get very cumbersome if your inout-format changes - e.g. if you have doubles instead of ints. — MakePeaceGreatAgain, Feb 25 '19 at 08:46
`JsonDataContractSerializer` can do this: https://learn.microsoft.com/en-us/dotnet/api/system.runtime.serialization.json.datacontractjsonserializer?view=netframework-4.7.2 — Ben, Feb 25 '19 at 08:51
What do you mean by "extra layer of complexity"? are you concerned about performance? JSON seems to be more readable, it is fast as well. it's designed to work with strings anyway... — M.kazem Akhgary, Feb 25 '19 at 08:52

score 19 · Accepted Answer · answered Feb 25 '19 at 08:46

You are correct - JSON can do this for you:

using System;
using Newtonsoft.Json;

namespace Demo
{
    class Program
    {
        static void Main()
        {
            string test = "[123,234,345,456]";

            var result = JsonConvert.DeserializeObject<int[]>(test);

            // This prints "123, 234, 345, 456"

            Console.WriteLine(string.Join(", ", result));

            string andBackAgain = JsonConvert.SerializeObject(result);

            // This prints "[123,234,345,456]"

            Console.WriteLine(andBackAgain);
        }
    }
}

Exactly what I was looking for but was unaable to produce. Thank you. — iiminov, Feb 25 '19 at 14:25

score 0 · Answer 2 · answered Feb 25 '19 at 08:49

If your intention is to parse numbers with double quotes then

    string input = @"[123,234,345,456]";
    string pattern = @"\d+";
    var result = Regex.Replace(input, pattern, "\"$&\"");
    result.Dump();
    //["123","234","345","456"]

or to parse whole object inside array braces

    string input = @"[123,234,345,456]";
    string pattern = @"(\d+\s*,?\s*)+";
    var result = Regex.Replace(input, pattern, "\"$&\"");
    result.Dump();
    //["123,234,345,456"]

Better way to converting string [123,234,...] to List and back

2 Answers2