Summary -

In this topic, we described about the below sections -

What is Variable?

Variable are named data objects that refers to the memory location allocated during the program execution for processing. Variable contains data and act as a referring name for the data.

We can modify data, change data, clear data or apply operations on the data with help of the variable. Each variable should declare with a data type along with size in ABAP.

A variable must be declared before using it. A variable memory always allocated before the program execution and destroys once the program execution completed. No permanent memory allocated to a variable.

Now let us see the variable declaration syntax below -

Syntax -

DATA: Variable-name TYPE data-type [VALUE data-value].

  • Variable-name - Specifies the variable name. Variable name length can be up to 30 characters.
  • Data-type - Specifies the data type. We have discussed data types in the previous chapter.
  • Data-value - Value that initially assigned to the variable during the declaration.

Variable Naming Convention -

Variable naming convention standard is project dependentant and may vary from project to project. Below is one of the standard ABAP variable naming convention -

Syntax -

{Visibility_character}{data_type_character}_{Remaining_field_name}

Below table specifies the list of options available for visibility_character.

Visibility_character Information

Below table specifies the list of options available for data_type_character.

data_type_character Information

Remaining_field_name can be any combination of alpha-numeric characters of developer choice based on the variable usage.

Variable types -

ABAP supports 5 different variable types based on the structure and durability in the program. Those are -

Variable Types Description
Local variables Local variables are very local to the program or function or include etc,.
Static variables Static variables are initialized only once and carries out the data until the end of the program execution.
Reference variables Reference variables contain the references of other variables to perform data manupulations.
System variables System variables are predefined variables and accessed by all the programs in SAP environment.
Structured variables Structure variable is variable that declared of structure data type.

Example -

Write a simple program to get clear understanding of local, static variables working.


Code - 

*&---------------------------------------------------------------------*
*& Report  Z_LOCAL_STATIC
*&---------------------------------------------------------------------*
*& Program coded by TUTORIALSCAMPUS
*&---------------------------------------------------------------------*

REPORT  Z_LOCAL_STATIC.

WRITE: 'local variable - static variable'.

* Loop for 5 times.
DO 5 TIMES.

* Perform addition subroutine.
  PERFORM addition.

ENDDO.

* Subroutine addition coding.
FORM addition.

*  Initializing local variable.
   DATA lv_local TYPE i VALUE 99.

*  Initializing static variable.
   STATICS lv_static TYPE i VALUE 99.

*  Adding 1 to local variable.
   lv_local = lv_local + 1.

*  Adding 1 to static variable.
   lv_static = lv_static + 1.

*  Display local, static variables.
   WRITE: / lv_local, lv_static.

ENDFORM.

Output -

Local and Static Variable example Output

Explaining Example -

In the above example, each and every statement is preceeded with a comment to explain about the statement. Go through them to get clear picture of example code.

Coming to output, lv_local variable is declared in the subroutine and it is local to the addition subroutine. So the lv_local variable got initialized everytime whenever addition subroutine called.

In the above example, we have called addition subroutine 5 times. So, the lv_local variable got initialized with 99 on every time and adds 1 to 99 and display output 100. The same happens for 5 times.

Coming to static variable output, lv_static variable is declared in the subroutine and it is static to the addition subroutine. So the lv_static variable got initialized only when the first time addition subroutine called. During the first sobroutine call, the lv_static variable initialized with 99, adds 1 to 99 and result 100 is displayed for the first time. For the second time subroutine call, the value 100 from the first call retains in lv_static variable, adds 1 to 100 and result 101 displayed in second iteration.

In the above example, we have called addition subroutine 5 times. So, the lv_static variable value incementing by 1 every time and display output 100, 101, 102, 103 and 104.