如何拆分特定格式的字符串并将其分配给c#中的变量？

Question

I am very new to C# and would need some advice on how to approach the following problem.

I have the following.

string input = "{1, 'hello', 1, 3}, {2, 'othello', 0, 2}"

There could be cases where there is just one {} or more in the input string.

I want to be able to to split the input string on the two or more {} and create an instance of the class Data and add each of the new instances to a List<Data> mydatalist() .

I have the following declaration of the Data class. I am not sure on how to split the input string and create the Data class instance from it.

public partial class Data
{
    private:
    int id;
    string desc;
    int state;
    int res;

    public:
    Data(int idval, string indesc, int instate, int inres)
    {
        id=idval; desc=indesc; state=instate; res=inres; 
    }
}

In the end, my List<Data> mydatalist() would contain two Data class objects with the respective fields declared accordingly.

void CreateInstances(string result)
{
   var temp = result.Split(); // This gives me every index?
}

Any help wold be appreciated.

Answer 1

• Use a regular-expression for the repeating { <number>, <string>, <number>, <number> } part.
• I strongly recommend using an immutable POCO instead of a mutable type as your code does.
• You said you're new to C# but I don't know if you're new to regular-expressions and parsing in genreal, but the regular-expression "matches" your input text and allows the program to extract data from it. Think of it as a more powerful form of a wildcard or glob search "foo*.txt" you may have seen already.
  • (\d+) means "match decimal digits"
  • \s* means "expect optional whitespace here"
  • '(.*?)' means "read every character between two quotes as a single value"
  • You can try it out online here: https://regex101.com/r/mesMGG/1
• The Match.NextMatch() method and Match.Successful properties allows the same regex to be run multiple times over an input string.
• The matched text are returned as String values in Match.Groups[] .
  • Note that Match.Groups[0] is always the whole input string, which is why my code starts at index 1 instead of 0 .
  • Because they're String values, you need to use Int32.Parse or Int32.TryParse to convert them to Int32 values.

Like so:

class Data
{

    public Data( Int32 id, String description, Int32 state, Int32 res )
    {
        this.Id = id;
        this.Description = description;
        this.State = state;
        this.Res = res;
    }

    public Int32 Id { get; }
    public String Description { get; }
    public Int32 State { get; }
    public Int32 Res { get; }
}

public static List<Data> ParseData( String input )
{
    RegEx r = new Regex( @"\{\s*(\d+)\s*,\s*'(.*?)'\s*,\s*(\d+)\s*,\s*(\d+)\s*\}" );

    List<Data> list = new List<Data>();

    Match m = r.Match( input );
    while( m.Success )
    {
        Int32  id    = Int32.Parse( m.Groups[1].Value, NumberStyles.Integer, CultureInfo.InvariantCulture );
        String desc  = m.Groups[2].Value;
        Int32  state = Int32.Parse( m.Groups[3].Value, NumberStyles.Integer, CultureInfo.InvariantCulture );
        Int32  res   = Int32.Parse( m.Groups[4].Value, NumberStyles.Integer, CultureInfo.InvariantCulture );

        Data d = new Data( id, desc, state, res );
        list.Add( d );

        m = m.NextMatch();
    }

    return list;
}

Used like so:

List<Data> list = ParseData( "{1, 'hello', 1, 3}, {2, 'othello', 0, 2}" );

Answer 2

If you use Newtonsoft JSON.NET and change your input to JSON:

string dataString = "[{id: 1, desc: "hello", state: 1, res: 3}, {id: 2, desc: "othello", state: 0, res: 2}]"
var dataObject = Newtonsoft.Json.JsonConvert.DeserializeObject<Data>(dataString );

Answer 3

This should help.

This deals with dest having spaces.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

(...)

public static void Main(string[] args)
{

    string input = "{1, 'Western Australia', 1, 3}, {2, 'othello', 0, 2}";
    var pattern = "{(.*?)}";
    var matches = Regex.Matches(input, pattern);

    var separated = matches
                .Select(m => m.Groups[1].ToString())
                .ToList();

    var os = new Program().CreateInstances(separated).ToList();
}

IEnumerable<Data> CreateInstances(IEnumerable<string> separated)
    => separated.Select(o =>
        {
            var parts = o.Split(',').Select(s => s.Trim()).ToList();
            return new Data(
                int.Parse(parts[0]),
                parts[1].Trim('\''),
                int.Parse(parts[2]),
                int.Parse(parts[3]));
        });

---

Test

Code

// I made fields public just to print the values
foreach(var o in os ) Console.WriteLine($"id={o.id}, desc={o.desc}, state={o.state}, res={o.res}");

Output

// .NETCoreApp,Version=v3.0
id=1, desc=Western Australia, state=1, res=3
id=2, desc=othello, state=0, res=2

Answer 4

Here's an example just doing standard string manipulation w/ a few assumptions about the standardization of your data strings.

using System;
using System.Collections.Generic;

namespace ConsoleApp1
{
class Program
{
    static void Main(string[] args)
    {            
        string input = "{1, 'hello', 1, 3}, {2, 'othello', 0, 2}";

        //get the first start open curly
        int start = input.IndexOf('{');

        List<Data> list = new List<Data>();
        while (start >= 0)
        {
            //find position of first close curly after our open curly
            var end = input.IndexOf('}', start);

            //get all values between curlys
            var setValues = input.Substring(start + 1, (end - 1) - start);

            //split them into array
            var split = setValues.Split(',');

            list.Add(new Data()
            {
                Id = Convert.ToInt32(split[0]),
                Desc = split[1],
                State = Convert.ToInt32(split[2]),
                Res = Convert.ToInt32(split[3])
            });

            //get next open curly based off of most recent closed curly position
            start = input.IndexOf('{', end);
        }
    }
}
    public class Data
    {
        public int Id { get; set; }
        public string Desc { get; set; }
        public int State { get; set; }
        public int Res { get; set; }
    }
}