Variables & Declarations in ABAP

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Variables

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Objectives

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• Understand what a VARIABLE is in ABAP
• Know how to declare and correctly name a VARIABLE
• Identify available DATA TYPES
• Distinguish between TYPE and LIKE syntax

Definition

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A VARIABLE is a memory space associated with a name that allows storing a temporary value.
This value can change during program execution.

A VARIABLE works like a labeled box, a named container: you can place data in it, modify it, or replace it.

Declaration with DATA

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Simple Declaration

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WRITE:/ ’ - SIMPLE DECLARATION…'.

DATA lv_variable TYPE string.

• DATA declares a VARIABLE.
• lv_variable is its name.
• TYPE string indicates that it stores a character string.

Successive Declarations

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WRITE:/ ’ - SUCCESSIVE DECLARATION…'.

DATA: lv_variable1 TYPE string,
      lv_variable2 TYPE i,
      lv_variable3 TYPE c1.

• DATA: declares a succession of VARIABLES.
• lv_variable1 → text (character string)
• lv_variable2 → integer (number)
• lv_variable3 → fixed character of 10 characters

Grouping declarations makes code more readable and facilitates maintenance.

Naming Conventions

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Naming a VARIABLE is like naming a folder on your computer: a precise name makes it easy to find what it contains.

TYPE vs LIKE

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Two syntax options exist for declaring a VARIABLE.

TYPE

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DATA lv_variable TYPE string.

Explicitly defines the data type.

LIKE

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DATA lv_other_variable LIKE lv_variable.

Copies the same type and length as another VARIABLE.

TYPE → reference to a data type.
LIKE → reference to another VARIABLE.

WRITE:/ ’ - DECLARATION… LIKE…'.

DATA: lv_variable4 TYPE string,
      lv_variable5 LIKE lv_variable4,
      lv_variable6 LIKE lv_variable5.

Basic Data Types

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Type C (character)

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WRITE:/ ’ - TYPE CHAR…'.

DATA: lv_firstname   TYPE char255,
      lv_lastname(9) TYPE c.

lv_firstname = 'John'.
lv_lastname  = 'Wick'.

Stores fixed text strings (names, addresses, labels, etc.).

Type I / N / NUMC (numeric)

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WRITE:/ ’ - TYPE INTEGER…'.

DATA: lv_integer        TYPE i,
      lv_year           TYPE n,
      lv_numeric_string TYPE numc2.

lv_integer = 10.
lv_year = 2025.
lv_numeric_string = 31000.

I = actual numeric value, used for calculation.
N / NUMC = text containing only digits.

Type D (date) and SY-DATUM

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WRITE:/ ’ - TYPE DATE…'.

DATA: lv_date  TYPE d,
      lv_date2 TYPE datum.

lv_date  = sy-datum.
lv_date2 = 19861102.

Format: YYYYMMDD
Example: 20251029 → October 29, 2025.

Type T (time) and SY-UZEIT

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WRITE:/ ’ - TYPE TIME…'.

DATA: lv_time  TYPE t,
      lv_time2 TYPE uzeit.

lv_time  = sy-uzeit.
lv_time2 = 183045.

Format: HHMMSS
Example: 183045 → 6:30:45 PM.

Type F (fixed floating point) / FLOAT (variable precision)

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WRITE:/ ’ - TYPE FLOAT…'.

DATA: lv_f TYPE f,
      lv_float TYPE float.

lv_f = '123455.12'.
lv_float = '123455.12'.

Type F handles decimal values with defined precision. As for FLOAT type, it’s a real value with variable precision, useful for scientific calculations.

Type DECFLOAT

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WRITE:/ ’ - TYPE DECFLOAT…'.

DATA: lv_decfloat TYPE decfloat34.

lv_decfloat = '12345.67890123456789012345678901234'.

Precision up to 34 significant digits - used for financial calculations.

Type P (packed decimal)

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WRITE:/ ’ - TYPE PACKED DECIMAL…'.

DATA: lv_pack TYPE p DECIMALS 2.

lv_pack = '1234.56'.

Compact numeric type, ideal for financial amounts.

Type STRING

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WRITE:/ ’ - TYPE STRING…'.

DATA: lv_string TYPE string.

lv_string = 'Hello World'.

Variable length, useful for dynamic texts.

Type BOOLEAN / ABAP_BOOL

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WRITE:/ ’ - TYPE BOOLEAN…'.

DATA: lv_bool    TYPE boolean,
      lv_boolean TYPE abap_bool.

lv_bool    = abap_true.
lv_boolean = abap_false.

Possible values: abap_true (true) / abap_false (false)

Always initialize explicitly:

DATA lv_flag TYPE boolean VALUE abap_true.

Type XFELD

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WRITE:/ ’ - TYPE XFELD…'.

DATA: lv_xfeld TYPE xfeld VALUE 'X'.

lv_xfeld = 'X'. "Check
lv_xfeld = ' '. "Uncheck

Represents SAP checkboxes:
‘X’ = checked, ’ ’ = unchecked.

Prefer XFELD to visually represent binary states in SAP screens.

Best Practices

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Clear names and rigor in declaration prevent 80% of logic errors in ABAP.

Summary

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• A VARIABLE stores a modifiable value during the program.
• It’s declared with DATA and follows strict conventions (lv*, gv*).
• TYPE and LIKE are used to define or copy a type structure.
• Most used types: C, I, N, NUMC, D, T, F, STRING, BOOLEAN, XFELD.
• Always initialize, document, and clearly name VARIABLES.

Constants

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Objectives

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• Understand what a CONSTANT is in ABAP
• Know how to declare a CONSTANT with CONSTANTS
• Apply naming conventions
• Identify possible data types
• Differentiate CONSTANTS and VARIABLES

Definition

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A CONSTANT is a fixed value associated with a name.
Unlike a variable, its value never changes during program execution.

A CONSTANT is like a fixed marker on a map: it doesn’t move.
A variable, on the other hand, can move.

Imagine a watch whose battery is dead: the value remains frozen.
A variable would be a normal thermometer, which changes with temperature.

Declaration with CONSTANTS

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Simple Syntax

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WRITE:/ ’ - SIMPLE DECLARATION…’.

CONSTANTS: lc_valeur_const TYPE i VALUE 10.

• CONSTANTS: keyword to declare a CONSTANT
• lc_valeur_const: name of the CONSTANT
• TYPE i: integer data type
• VALUE 10: fixed value assigned to the CONSTANT

It’s like setting multiple markers on the same map.

The CONSTANTS keyword accepts a list separated by : to declare multiple consecutive CONSTANTS.

Successive Declarations

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WRITE:/ ’ - SUCCESSIVE DECLARATION…'.

CONSTANTS: lc_max_users TYPE i VALUE 100,
           lc_timeout   TYPE i VALUE 30,
           lc_flag      TYPE abap_bool VALUE abap_false.

• Use the CONSTANTS: syntax followed by a comma-separated list to declare multiple CONSTANTS in a single statement.
• Each CONSTANT must specify TYPE and VALUE or use LIKE + VALUE.

Grouping CONSTANTS by theme (parameters, codes, formats) helps with maintenance.

Naming Conventions

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A CONSTANT is a fixed sign: its label must be clear because it will never change.

TYPE vs LIKE

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TYPE

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CONSTANTS: lc_valeur_const TYPE i VALUE 10.

• Explicitly defines the type.

LIKE

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DATA: lv_variable TYPE i VALUE 5.
CONSTANTS: lc_valeur_const LIKE lv_variable VALUE 20.

• Copies the type of another variable, but remains immutable.

TYPE → you choose the shape of your box.
LIKE → you copy someone else’s box, but you can’t open it anymore.

Data Types for Constants

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Integer / Numeric / NUMC

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WRITE:/ ’ - TYPE INTEGER, N, NUMC…'.

CONSTANTS: lc_integer        TYPE I VALUE 10,
           lc_max_value      TYPE N VALUE 9999,
           lc_account_number TYPE NUMC10 VALUE 1234567890.

• I → integers for calculations
• N / NUMC → numeric text (e.g., postal code)

Float / F

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WRITE:/ ’ - TYPE F, FLOAT…'.

CONSTANTS: lc_fixed_value TYPE F VALUE '1234.56',
           lc_float_value TYPE FLOAT VALUE '1234.567890123456789'.

• F → fixed decimals
• FLOAT → variable precision (scientific)

DECFLOAT

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WRITE:/ ’ - TYPE DECFLOAT…'.

CONSTANTS: lc_decfloat TYPE DECFLOAT34 VALUE '12345.67890123456789012345678901234'.

• High precision, useful for financial calculations.

String

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WRITE:/ ’ - TYPE STRING…'.

CONSTANTS: lc_string TYPE STRING VALUE 'Hello, World!'.

• Variable-length text, non-modifiable.

Character

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WRITE:/ ’ - TYPE CHAR…'.

CONSTANTS: lc_char TYPE C LENGTH 1 VALUE 'F'.

• Fixed character (e.g., initial, status).

Boolean / ABAP_BOOL

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WRITE:/ ’ - TYPE BOOLEAN…'.

CONSTANTS: lc_bool TYPE BOOLEAN VALUE ABAP_TRUE,
           lc_boolean TYPE ABAP_BOOL VALUE ABAP_FALSE.

• Logical values: true or false.

Date (D) and SY-DATUM

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WRITE:/ ’ - TYPE DATE…'.

CONSTANTS: lc_date1 TYPE D VALUE SY-DATUM,
           lc_date2 TYPE D VALUE 19861102.

• Format YYYYMMDD.

Time (T) and SY-UZEIT

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WRITE:/ ’ - TYPE TIME…'.

CONSTANTS: lc_time1 TYPE T VALUE SY-UZEIT,
           lc_time2 TYPE T VALUE 183045.

• Format HHMMSS.

Packed Decimal (P)

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WRITE:/ ’ - TYPE PACKED…'.

CONSTANTS: lc_pi TYPE P DECIMALS 2 VALUE '3.14'.

• Fixed value for amounts or financial calculations.

XFELD

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WRITE:/ ’ - TYPE XFELD…'.

CONSTANTS: lc_xfeld TYPE XFELD VALUE 'X'.

• ‘X’ = checked / ’ ’ = unchecked.

Best Practices

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Always replace repeated numbers or texts with a CONSTANT: your code will be clearer and easier to maintain.

Summary

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• A CONSTANT keeps a fixed value throughout the program.
• Declared with CONSTANTS ... VALUE.
• TYPE and LIKE define or copy an existing type.
• Main types: I, N, NUMC, F, DECFLOAT, STRING, C, BOOLEAN, D, T, P, XFELD.
• Always prefer a CONSTANT to a “hardcoded” value.
• CONSTANTS improve clarity, security, and maintainability of ABAP code.

Field-symbols

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Objectives

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• Understand what a FIELD-SYMBOL is in ABAP
• Know how to declare a FIELD-SYMBOL with FIELD-SYMBOLS
• Apply naming conventions for FIELD-SYMBOLS
• Differentiate FIELD-SYMBOL, VARIABLE, and CONSTANT
• Understand the assignment principle and why it’s mandatory

Definition

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A FIELD-SYMBOL is a special variable that acts as a pointer or reference to a memory area.
Modifying a FIELD-SYMBOL means directly modifying the pointed data, not the FIELD-SYMBOL itself.

In other words, it doesn’t contain its own value but references another variable, a table field, or an expression result.

A FIELD-SYMBOL is like an arrow on a map: the arrow doesn’t contain the object, it just indicates where it’s located.

Moving or changing the arrow doesn’t change the object; but using the arrow to modify the area directly changes the object.

Purpose

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• Traverse internal tables without copying rows.
• Work on dynamic or unknown structures in advance.
• Gain performance and flexibility in code.

Principle

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• A FIELD-SYMBOL acts as a temporary alias.
• It’s declared with FIELD-SYMBOLS, then associated with a variable using ASSIGN.
• After association, any modification via the FIELD-SYMBOL directly modifies the original data.

Declaration with FIELD-SYMBOLS

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Simple Syntax

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FIELD-SYMBOLS <lfs_> TYPE any.
ASSIGN <variable> TO <lfs_>.

IF <lfs_> IS ASSIGNED.
  <lfs_> = 'New value'.
ENDIF.

Example:

DATA lv_text TYPE string VALUE 'Hello'.
FIELD-SYMBOLS <lfs_string> TYPE string.

ASSIGN lv_text TO <lfs_string>.
<lfs_string> = 'Hi'.

WRITE:/ <lfs_string>.

Multiple Declaration

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FIELD-SYMBOLS: <lfs_field1> TYPE any,
               <lfs_field2> TYPE any,
               <lfs_field3> TYPE any.

• <lfs_integer>: name of the FIELD-SYMBOL between angle brackets < >
• TYPE: type of pointed data (i, string, any, etc.)
• Tip: TYPE ANY can be used if the FIELD-SYMBOL will point to different data types or an ABAP object.

TYPE ANY is very useful for FIELD-SYMBOLS that will point to different types of objects or dynamic structures.

The Assignment Principle

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A FIELD-SYMBOL contains no value before being assigned.
Any attempt to write directly without assignment causes a CX_SY_REF_IS_INITIAL error.

Invalid Example

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FIELD-SYMBOLS <lfs_num> TYPE i.
<lfs_num> = 10.  "ERROR! Not assigned

Correct Example

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DATA lv_number TYPE i.
FIELD-SYMBOLS <lfs_num> TYPE i.

ASSIGN lv_number TO <lfs_num>.
<lfs_num> = 10.  "OK, directly modifies lv_number

• ASSIGN: binds the FIELD-SYMBOL to an existing variable.
• Then, any modification via the FIELD-SYMBOL affects the target variable.
• Analogy: we point the arrow at the correct sign before being able to modify it.

Perfect Example

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DATA: lv_prenom2 TYPE string VALUE 'FRED'.
FIELD-SYMBOLS: <lfs_prenom> TYPE string.

ASSIGN lv_prenom2 TO <lfs_prenom>.

IF <lfs_prenom> IS ASSIGNED.
  <lfs_prenom> = 'PIERRE'.
  WRITE:/ <lfs_prenom>,
      / lv_prenom2.
ENDIF.

To be sure that a Field-Symbol is assigned, you can check the assignment as in the example above via the condition

IF <lfs_> IS ASSIGNED.
  "Processing here if condition is true
ENDIF.

Field-symbol and Object

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For information for the CLASS module

For an object:

DATA lo_obj TYPE REF TO zcl_my_class.
FIELD-SYMBOLS <lfs_obj> TYPE zcl_my_class.

CREATE OBJECT lo_obj.
ASSIGN lo_obj->* TO <lfs_obj>.  "Now <lfs_obj> points to the object

Naming Conventions

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Usage

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• Always assign before use:

ASSIGN lv_variable TO <lfs_integer>.

• Any modification via <lfs_integer> will directly affect lv_variable.
• Never write to an unassigned FIELD-SYMBOL.

Summary

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• FIELD-SYMBOL = pointer to a memory area, not a direct value
• Declare with FIELD-SYMBOLS <name> TYPE ...
• Always assign with ASSIGN before any use
• Prefixes <lfs_> (local) or <gfs_> (global) for readability
• TYPE ANY useful for objects or variable types
• General analogy: arrow on a map, it points to the target, modification is done on the target, not on the arrow.