DYNAMIC ARRAY

DYNAMIC ARRAY data type works the same way as ARRAY data type, but it has some additional features. Use the following syntax to declare a single-dimensional dynamic array of variables:

Dynamic arrays differ from traditional 4GL program arrays in that they do not have a fixed size. Attempts to into a dynamic array will cause the array to resize automatically, whereas it is impossible to write beyond the bounds of a static program array.

A multi-dimensional dynamic array is declared using the following syntax:

There exists a number of restrictions imposed on multi-dimensional dynamic arrays. They are as follows:

1.     .getLength() method is not supported. E.g., for:

DEFINE a DYNAMIC ARRAY WITH 2 DIMENTIONS OF datatype

valid usage:   

a[index].getLength()

invalid usage, resulting in a compile time error:  

a.getLength() 

2.     DISPLAY ARRAY statement can be used only for the arrays of the RECORD data type display.

3.     The same limitations as for the static arrays:

• definition: array length must always be greater than '0', otherwise an application fails to compile;

• verification of indices it bounds: on an attempt to access by the index falling outside beyond the range, a compile time error occurs

A two-dimensional dynamic array declaration:

DEFINE x DYNAMIC  ARRAY WITH 2 DIMENSIONS OF INTEGER

...

FOR i = 1 TO 100

FOR j = 1 TO 100

      LET x[i,j] = i*j MOD 7

END FOR

END FOR

A three-dimensional dynamic array declaration:

DEFINE x DYNAMIC  ARRAY WITH 3 DIMENSIONS OF INTEGER

...

FOR i = 1 TO 10

FOR j = 1 TO 10

FOR k = 1 TO 10

      LET x[i,j,k] = i*j*k MOD 13

END FOR

END FOR

END FOR

Here is the list of methods used to manipulate variables of a DYNAMIC ARRAY type: