Arrays in ILE RPG (RPG IV) Run Time Arrays, Compile Time Arrays
Arrays in RPGLE
In RPG-ILE, we have arrays to store similar types of variables. An array is declared by the keyword Dimension. We specify the size of array as the parameter of the Dim() keyword. A typical array will be declared as below.
Two types of Arrays in RPGLE
DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords DW@RTime S 5P 0 Dim(5)
Just like any other programming lanuage, the arrays in RPGLE are referenced using their index. To access the first element of the above array we have to use W@RTime(1), and so on. This will be explained by the example below which first populates the array and then displays the value of each array element one by one.
DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords++++++++++++ DW@RTime S 5P 0 Dim(5) Inz D @Indx S 1P 0 Inz ** Populate the error CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result++++++++ C Do 5 @Indx C Eval W@RTime(@Indx) = @Indx + 200 C EndDo ** Access the array elements C Do 5 @Indx C W@RTime(@Indx)Dsply C EndDo ** C Return
The output of the above example is given below.
DSPLY 201 DSPLY 202 DSPLY 203 DSPLY 204 DSPLY 205
Two types of Arrays in RPGLE
In ILE RPG we've two types of arrays.
- Runtime Array
- Compile time Array
The array we have just seen is a run time array. As the array elements are populated at the run time. In the case of compile time arrays, the arrays must be populated at the time of compilation. The compile time arrays of RPGLE are used mainly to store error messages. Though this is not limited to error message population only. The data of a compile time array is defined at the end of all the source codes at the bottom. The compile time array is declared as below.
Example of a compile time array
.....DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++
DW@RTime S 5P 0 Dim(5) CTDATA
D @Indx S 1P 0 Inz
** Access the array elements
.....CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result+
C Do 5 @Indx
C W@RTime(@Indx)Dsply
C EndDo
**
C Return
**CTDATA W@RTime
00101
00102
00103
00104
00105
Notice the initialization of the array elements. The **CTDATA specifies that the array elements of the array W@RTime are being declared below this line. If you have to specify multiple compile time array then you should specify this for each of compile time arrays. The output of the above program is given below.
DSPLY 101 DSPLY 102 DSPLY 103 DSPLY 104 DSPLY 105
Notice the difference between the declarations of the compile and runtime arrays. In compile time arrays we have to specify another keyword CTDATA alongwith the dimension. This keyword specifies that the array stores Compile Time DATA.
We can define multiple array elements in one line. For this we have to specify that there are multiple subrecords in each of records at the bottom. We do this using the keyword PerRcd. Notice that the second record should begin immediately after the first record. i.e if the size of each of the array elements is defined as 10A. then the second element of this array should begin exactly at 11th position on the record. Though you may keep it blank(Which is valid value)
The example below demonstrates a compile time array with multiple array elements defined in each records.
Example showing the PerRcd and CTDATA keywords on a compile time array.
.....DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++
DW@RTime S 5P 0 Dim(4) CTDATA PerRcd(2)
D @Indx S 1P 0 Inz
** Access the array elements
.....CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result++++++++Len
C Do 4 @Indx
C W@RTime(@Indx)Dsply
C EndDo
**
C Return
**CTDATA W@RTime
0010100102
0010300104
The output of the above example is as given below. Here, notice how the array data is
given. The first data occupies the first five positions of the record. Immediately after this, the second array element's value follows. Similary the rest of two values have been populated from the second record.
DSPLY 101 DSPLY 102 DSPLY 103 DSPLY 104
- 9792 reads