The DISPLAY ARRAY statement displays program array values in a screen array, so that the user can scroll through the screen
record array is the identifier of a program array of RECORD variables.
screen array is the identifier of a screen array.
To use the DISPLAY ARRAY statement, you must do the following:
Define the screen array in the form specification file.
Use DEFINE to declare an array of program records, whose members correspond in
name, data type, and order to the screen array fields.
Open and display the screen form with either of the following:
The OPEN FORM and DISPLAY FORM statements.
The OPEN WINDOW statement with the WITH FORM clause.
Fill the program array with data to be displayed, counting the number of
program records being filled with retrieved data.
Call the SET_COUNT(x) function, with x the number of filled records.
Use the DISPLAY ARRAY statement to display the program array values in the
screen array fields.
The SET_COUNT( ) function sets the initial value of the ARR_COUNT( ) function.
If you do not call SET_COUNT( ), then 4GL cannot determine how much data to
display, and so the screen array remains empty.
The DISPLAY ARRAY statement binds the screen array fields to the member
records of the program array. The number of variables in each record of the program
array must be the same as the number of fields in each screen record (that is,
in a single row of the screen array). Each mapped variable must have the same
data type or a compatible data type as the corresponding field.
The size of the screen array (from the form specification file) determines the
number of program records that 4GL displays at one time on the screen. The
size of the program array determines how many retrieved rows of data the program
can store. The size of the program array can exceed the size of the screen
array. In this case, the user can scroll through the rows on the form.
When 4GL encounters a DISPLAY ARRAY statement, it does the following:
Displays the program array values in the screen array fields.
Moves the cursor to the first field in the first screen record.
Waits for the user to press a scroll key (by default, F3 to scroll forward, or
F4 to scroll backwards) or the Next Page or Previous Page keys or mouse
buttons, or to choose Accept key.
Since the DISPLAY ARRAY statement does not terminate until the user presses
the Accept or Interrupt key, you may want to display a message informing the
By default, 4GL displays variables and constants as follows:
Right-justifies number values in a screen field.
Left-justifies character values in a screen field.
Truncates the displayed value, if a character value is longer than the field.
Fills the field with asterisks ( * ) to indicate an overflow, if a number
value is larger than the field can display.
If the field contains a BYTE value, displays <byte value> in the field.
The ON KEY Blocks
The ON KEY keywords specify a block of statements to be executed when the user
selects one of the specified keys. This is the syntax of the ON KEY block:
key name is one or more of these keywords, in uppercase or lowercase letters, separated
by commas, to specify a key:
ESC or ESCAPE
F1 through F64
CONTROL-char (except A, D, H, I, J, L, M, R, or X)