How to create a Class List with different numbers of inputs in C#

Question

I'm working on my first real c# project and I have faced a problem with my way of creating List based on a Class, which I have no idea how to solve.

I’m trying to write some code, which takes an input file (txt/csv) of multiple constructions with multiple layers, put it into my program, and later write the constructions into a new txt/csv file.

When having the same numbers of layers, it works fine. But when the constructions have different numbers of layers it causes trouble and I get a “System.IndexOutOfRangeException”. My question is: Can I make the Class which I’m basing my List on, dynamic (I don’t know if it is the technical term), so it work with different numbers of inputs? Both when Adding the construction to the program and when I write it to a new file?

My code is:

class Program
{
    static void Main(string[] args)
    {
        // Filepath for the input and output file
        string filePathIn_constructions = @"C:\Library\Constructions.txt";
        string filePathOut = @"C:\Library\EPlus_Inputfile.txt";

        // Creating a list of constructions based on the class. The list is made from the file "filePathIn_constructions"
        List<Construction> allConstructions = new List<Construction>();
        List<string> lines_constructions = File.ReadAllLines(filePathIn_constructions).ToList(); // add it to a list

        // Adding all the data from the fil to the variable "allConstructions"
        foreach (var line in lines_constructions)
        {
            string[] entries = line.Split(',');

            Construction newConstruction = new Construction();
            newConstruction.EIndex = entries[0];
            newConstruction.Name = entries[1];
            newConstruction.Layer1 = entries[2];
            newConstruction.Layer2 = entries[3];
            newConstruction.Layer3 = entries[4];
            newConstruction.Layer4 = entries[5];
            newConstruction.Layer5 = entries[6];
            
            allConstructions.Add(newConstruction); // Add it to our list of constructions
        }

        List<string> output = new List<string>();

        foreach (var x in allConstructions) // Printing the new 
        {
            output.Add($"{x.EIndex}, {x.Name}, {x.Layer1}, {x.Layer2}, {x.Layer3}, {x.Layer4}, {x.Layer5}");
            
        }
        File.WriteAllLines(txtFilePathOut, output);
    }
}

My Class for the Constructions is

public class Construction
{
    public string EIndex { get; set; }
    public string Name { get; set; }
    public string Layer1 { get; set; }
    public string Layer2 { get; set; }
    public string Layer3 { get; set; }
    public string Layer4 { get; set; }
    public string Layer5 { get; set; }      
}

An example of a input/output file could be

Construction,ConcreteWall,Concrete;
Construction,Brickwall1,Birck,Isulation,Brick;
Construction,Brickwall2,Birck,AirGap,Isulation,Brick;
Construction,Wood/Concrete Wall,Wood,Isulation,Concrete,Gypson;
Construction,Wood Wall,Wood,AirGap,Gypson,Isulaiton,Gypson;

I hope someone can help. Thanks.

Edit: I have to be able to excess the construction Name seperatly, because i'm using it to do some sorting of the.

Answer 1

It is because you are trying to reach a cell of an array that doesn't exist (documentation)

In your input/output file you have lines that have between 3 and 7 values, and you are building an array entries out of those values. This means that you will have arrays with between 3 and 7 cells

The problem is that right after creating those arrays you try to access on every array the cells 0, 1, 2... up to the 7th, even for arrays that have only 3 cells!

What you could do to fix this in a simple way is to add columns to have the same number of separator on each lines (you defined the separator of your lines as column with line.Split(',')). This way, every arrays that you will create will always have 7 cells, even if the value inside is null

Answer 2

public class Construction
{
    public string EIndex { get; set; }
    public string Name { get; set; }
    public List<string> Layers { get; set; } = new List<string>();     
}

        foreach (var line in lines_constructions)
        {
            string[] entries = line.Split(',');

            Construction newConstruction = new Construction();
            newConstruction.EIndex = entries[0];
            newConstruction.Name = entries[1];
            for (int i=2; i < entries.Length; i++) {
               newConstruction.Layers.Add(entries[i]); 
            }
            
            allConstructions.Add(newConstruction);
        }

        foreach(var x in allConstuctions) {
           File.AppendAllText(output, $"{x.EIndex}, {x.Name}, {string.Join(", ", x.Layers)}");
        }