[RESOLVED] accessing controls in a loop

[Tomexx]

Hi,
I have 6 pictureboxes on my form to display random pictures in.

I use several functions to load pictures, clear pictures etc. All of these functions have all 6 pictureboxes hardcoded.

For example:

private void ShowPics()
{
  this.pictureBox1.Image = this.pictures[this.rnd.Next(0, this.pictures.Length)];
  this.pictureBox2.Image = this.pictures[this.rnd.Next(0, this.pictures.Length)];
  this.pictureBox3.Image = this.pictures[this.rnd.Next(0, this.pictures.Length)];
  this.pictureBox4.Image = this.pictures[this.rnd.Next(0, this.pictures.Length)];
  this.pictureBox5.Image = this.pictures[this.rnd.Next(0, this.pictures.Length)];
  this.pictureBox6.Image = this.pictures[this.rnd.Next(0, this.pictures.Length)];
}

So if I wanted to add more pictureboxes I'd have to add lines to all those functions (for pictureBox6, 7, ...). Is there a more dynamic way to access each picturebox in a loop or arrayList or something?

[Hack]

How about an For i = 0 To 5 loop?

[karthikeyan]

hi look at this example:

foreach (Control ctrl in this.Controls)
            {
                if (ctrl is PictureBox)
                {
                    MessageBox.Show(ctrl.Name);
                }
            
            }

this will display al the picturebox names in your form.so like this u can loop through your contols in your page

[Tomexx]

Hack,
How would you use the for loop with separate controls?

karthikeyan,
This works for .Name but not for .Image of the picturebox

[timeshifter]

That's because it's still being seen as an object. Try something more like this:

foreach (Control ctrl in this.Controls)
{
   if (ctrl is PictureBox)
   {
      PictureBox pb = (PictureBox)ctrl; //cast it as a PictureBox to expose the right properties
      MessageBox.Show(pb.Image);
   }
}

[Tomexx]

Casting worked. Thanks.

I was hoping that I wouldn't have to go through all controls to find the boxes. I wonder how efficient would it be with lots of controls on the form.

[timeshifter]

No problem. Casting is an essential in C#. Probably the majority of type operations will involve some form of cast, otherwise C# won't know what type of object it's dealing with. Rather, it'll be dealing with the object type itself, and not the type you want it to.

[jmcilhinney]

If you want to loop through a number of controls then create an array of controls in code:

private PictureBox[] pictureBoxes;

public Form1()
{
    InitializeComponent();

    this.pictureBoxes = new PictureBox[] { this.pictureBox1,
                                           this.pictureBox2,
                                           this.pictureBox3 };
}