Question

i want to change color of edit control when enter edit and when exit from edit, i want do this by single function i dont want to add code for each edit in enter event or on exit event

Answer 1

yes like David and kobik said you just need to create event handlers for OnEnter and OnExit and assign the controls you wish to use them

for example

Add two TEdit’s to your form and in the constructor of the form do the following

__fastcall TTestForm::TTestForm(TComponent* Owner)
    : TForm(Owner)
{
    Edit1->OnEnter = EditEnter;
    Edit2->OnEnter = EditEnter;

    Edit1->OnExit = EditExit;
    Edit2->OnExit = EditExit;
}

Now Create the Enter and Exit event handlers like so

void __fastcall TTestForm::EditEnter(TObject *Sender)
{
    TEdit *Temp = (TEdit*)Sender;
    Temp->Color = clRed;
}

void __fastcall TTestForm::EditExit(TObject *Sender)
{
    TEdit *Temp = (TEdit*)Sender;
    Temp->Color = clGreen;
}

Thats it.