Breaking out of Recursion

san

I have a recursive Function, which recurses through all the Controls on the Windows form, checks if there is an Error Message Associated with a textbox, and then returns a bool.

How do I break out of the recursive function the first instance an error message is encountered? What am I doing wrong? Here is the code below -

public bool RX(Control Ctrlx)
        {
            bool InvalidIPX = false;

            try
            {
                foreach (Control G in Ctrlx.Controls)
                {
                    if (G is TextBox)
                    {
                        if (ErrorProvider.GetError(Ctrl).Length != 0)
                        {
                            InvalidIPX = true;
                            break;

                        }
                    }
                    RX(G);
                }
                return InvalidIPX;
            }

            catch (Exception ex)
            {
                Console.WriteLine("{0} Exception Caught", ex);
                return InvalidIPX;
            }
        }

4 Replies

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Robert Rybczynski18y ago
You need to check the return value from your recursive call and break out of the caller's loop if it returns the "I quit" value (I think it's == true in this case). Otherwise, you are only unwinding the stack to the level of the caller and the recursive function simply picks up with the next control.

Rob
Guest User18y ago
You're right - simple iteration won't find the nested controls.

I would suggest creating a class-level boolean variable (let's call it "foundError"), set it to false before starting the recursion, then set it to true when an error condition is discovered, and then check it before calling the recursive function.
san18y ago
I don`t think it`ll work for TextBoxes within other controls. Lets say textbox within a groupbox which is within a tabpage. That the reason I`m using recursion.

Here is my code -

public bool RX(Control Ctrlx)
        {
            bool InvalidIPX = false;

            foreach (Control G in Ctrlx.Controls)
            {
                if (G is TextBox)
                {
                    if (ErrorProvider.GetError(G).Length != 0)
                    {
                        InvalidIPX = true;
                        break;
                    }
                }

                else
                {
                        RX(G);
                }
            }
            return InvalidIPX; //Once it reaches here, I want to end the function. Right now it        // goes back to RX(G)
        }

When I step through it everything looks good, but when try to return the InvalidIPX it goes back to RX(G). I just want to return the bool and exit out of the function, stop the iteration. Something wrong with my logic?
Guest User18y ago
If you just want to iterate through all of the textboxes on a form, there's no need to use recursion at all. Just use a foreach loop in the Controls collection of the form, and once you've verified that the current control is a textbox, you can execute whatever validation you want on it:

            foreach (Control c in this.Controls)
            {
                if (c is TextBox)
                {
                    TextBox tb = (TextBox)c;
                   // validate tb contents here
                }
             }