In Delphi, arrays allow a developer to refer to a series of variables by the same name and to use a number (an index) to tell them apart.
In most scenarios, you declare an array as a variable — thus allowing for array elements to be changed at run-time.
Sometimes, however, you need to declare a constant array — a read-only array. You cannot change the value of a constant or a read-only variable. Therefore, while declaring a constant array you must also initialize it.
type TShopItem = record Name : string; Price : currency; end; const Days : array[0..6] of string = ( 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat' ) ; CursorMode : array[boolean] of TCursor = ( crHourGlass, crSQLWait ) ; Items : array[1..3] of TShopItem = ( (Name : 'Clock'; Price : 20.99), (Name : 'Pencil'; Price : 15.75), (Name : 'Board'; Price : 42.96) ) ;
This code declares and initializes three constant arrays, named: "Days," "CursorMode" and "Items."
- "Days" is a string array of six elements. Days returns the "Mon" string.
- "CursorMode" is an array of two elements, whereby declaration CursorMode[false] = crHourGlass and CursorMode = crSQLWait. "cr*" constants can be used to change the current screen cursor.
- "Items" defines an array of three TShopItem records.
Trying to assign a value for an item in a constant array raises the "Left side cannot be assigned to" compile time error.
For example, the following code will not successfully execute:
Items.Name := 'Watch'; //will NOT compile