To get all controls
public static IEnumerable<TControl> GetChildControls<TControl>(this Control control) where TControl : Control
{
var children = (control.Controls != null) ? control.Controls.OfType<TControl>() : Enumerable.Empty<TControl>();
return children.SelectMany(c => GetChildControls<TControl>(c)).Concat(children);
}
Now call this function
var allTextBoxes = this.GetChildControls<TextBox>();
foreach (TextBox tb in allTextBoxes)
{
if(tb.Text != ""){
//DO WHAT YOU WANT
}
}
To get all controls and sub-controls recursively of specified type, use this extension method:
public static IEnumerable<TControl> GetChildControls<TControl>(this Control control) where TControl : Control
{
var children = (control.Controls != null) ? control.Controls.OfType<TControl>() : Enumerable.Empty<TControl>();
return children.SelectMany(c => GetChildControls<TControl>(c)).Concat(children);
}
usage:
var allTextBoxes = this.GetChildControls<TextBox>();
foreach (TextBox tb in allTextBoxes)
{
tb.Text = ...;
}