Teach Yourself Borland C++ in 14 Days - portal

286 Day 8
TListBox class, the property that holds the list box items is called Items. For example, do this
exercise:
1. Create a new application and place a ListBox component on the form. Size the list
box as desired.
2. Change the Name property of the list box to ListBox.
3. Double-click on the background of the form (not on the list box). The Code
Editor displays the FormCreate() function.
4. Type the following code in the FormCreate() function:
char winDir[256], fileName[256];
GetWindowsDirectory(winDir, sizeof(winDir));
sprintf(fileName, “%s\\win.ini”, winDir);
ListBox->Items->LoadFromFile(fileName);
5. Click the Run button to compile and run the program.
When the program runs, the list box will contain the contents of your WIN.INI file. Using this
method, it’s easy to load a list box from any ASCII text data file. The ComboBox component
also has an Items property, and it works in exactly the same way.
You can add, delete, insert, and move items in a list box, combo box, or memo by calling the
Add(), Append(), Delete(), Insert(), and Move() methods of the TStrings class.
NOTE
How Add() performs depends on the value of the Sorted property. If
the Sorted property is set to true, Add() will insert the string where it
needs to be in the list of items. If Sorted is false, the new string will be
added at the end of the list.
You can clear a component of its contents by calling the Clear() method. You can access an
individual string by using the Strings property of TStrings and the array subscript operator.
For example, to retrieve the first string in a list of strings, you would use
Edit->Text = ListBox->Items->Strings[0];
Each string in a TStrings array contains the string itself and 4 bytes of extra storage. This extra
storage can be accessed through the Objects property. You can use the extra storage any way
you like. Let’s say, for example, that you were creating an owner-drawn list box that displayed
bitmaps. You could store the string in the usual way, plus store a pointer to the TBitmap object
in the Objects array.