How to execute string that gets returned by function

Question

I have a form that allows you to add multiple product ids to a buy. screenshot !

When you start the program here is what you see !

So every time you press a plus button another row appears !.

In order to avoid too many lines of code I decided to create a function so that it takes the number or the row where the plus button was pressed and adds 1 to it, so that the next row appears.

Right now it returns a string with the code, but I dont know how to execute it..

I have searched how to execute a string but the solution can never apply to my code.

//function
public string plus(int n)
        {
            string r="";

            r = "label" + (n + 1) + ".Visible = true;";
            r += "combobox" + (n + 1) + ".Visible = true;";
            r += "plusButton" + (n + 1) + ".Visible = true;";
            r += "minusButton" + (n + 1) + ".Visible = true;";

            return r;
        }

//plus button
private void plus1_Click(object sender, EventArgs e)
        {
            //code to execute (plus(1));
        }

Opinions and sugestions would be greatly appreciated, solutions even more!

Answer 1

Executing c# expression from string is really a bad idea and not what you want in this case. You could see this post for a detailed answer, but you really shouldn't.

I recommend you store all you component inside a collection like so.

public void plus(int n)
{
    labelsArray[n].Visible =
    comboboxArray[n].Visible =
    plusButtonArray[n].Visible =
    minusButtonArray[n].Visible = true;
}

private void plus1_Click(object sender, EventArgs e)
{
    plus(1);
}

You'd also need to declare new arrays to index your controls, and populate them with them. For exemple, for you labels array:

private Label[] labelsArray;


// Replace Form1 with the name of your class. This the constructor of your form.
public Form1()
{
    labelsArray = new [] {label1, label2, label3, ... };
}

Eventually, you could also create those controls dynamically instead of toggling their visibility.

Answer 2

You don't need to define the code as a string. There are much better ways to do that. If you don't want to save your controls in separate collections and all your controls are child controls of your Form , you can run the same code with the following function:

public void plus(int n)
{
    ((Label)this.Controls.Find("label" + (n + 1), false)[0]).Visible = true;
    ((ComboBox)this.Controls.Find("combobox" + (n + 1), false)[0]).Visible = true;
    ((Button)this.Controls.Find("plusButton" + (n + 1), false)[0]).Visible = true;
    ((Button)this.Controls.Find("minusButton" + (n + 1), false)[0]).Visible = true;
}