ABAP BASICs learn the basics of ABAP-1.ppt

ABAP/4
SAP - Programming Language

Introduction to ABAP/4
ABAP - Advanced Business Application Programming
ABAP/4 is the only tool used by SAP to develop all of its applications.
SAP customers use ABAP/4 for their own developments.
Some of the features of ABAP/4:
• ABAP/4 is multi-lingual.
• ABAP/4 contains a subset of SQL called open SQL.With open
SQL you can read and access data base tables regardless of the database
system you are using.
• ABAP/4 contains a special type of subroutine called function
module.
• ABAP/4 allows you to define and process internal tables that
exist only for the execution period of the program.

Main types of ABAP/4 programs:
1) Report programs
2) Dialog programs
Report programs:
A report program generates a list from database tables in a user defined
format. It does not alter the data in the database but only analyses(reads)
them.The results which can be displayed on the screen or sent to a
printer.
A report program can either be an online or background program.
Dialog programs
Dialog programs read and change database tables. It is also called as
Module pool programs.It accepts user information,processes the
information and updates the database. For this reason module pool
programs cannot be executed in background.

ABAP/4 Workbench tools.
The ABAP/4 development workbench contains tools you need to create
and maintain ABAP/4 programs.
The tools are:
1. Object browser
2. ABAP/4 Dictionary
3. ABAP/4 Editor
4. Function library
5. Screen painter
6. Menu painter

ABAP/4 Statements
Any ABAP/4 statement begins with a keyword and ends with a
period(.).
Keywords
A keyword is the first word of a statement. It determines the meaning of
the entire statement. There are five different types of keywords:
• Declarative keywords
• Modularization keywords
• Control keywords
• Calling keywords
• Operational keywords

The following list is an overview of the main features of data types and
objects:
Data types
Data types describe the technical properties of data objects.
There is no memory associated with data types.
Data objects
Each data object has a specific data type assigned to it.
Each data object occupies some space in memory.

ABAP BASICs learn the basics of ABAP-1.ppt

Elementary Data Types - User-Defined
User-defined elementary data types are based entirely on predefined
elementary data types. To define your own elementary data types, you
use the TYPES statement
Ex.
TYPES: NUMBER TYPE I.
DATA: NO_FLIGHTS TYPE NUMBER.

Structured Data Types
* Predefined ( Ex. Tables)
* User defined
· Field strings
· Internal tables
Field strings
A field string is a collection of other data types.
TYPES: begin of string,
name(10) type c,
age(3) type n,
end of string.
Internal tables
An internal table consists of several lines of the same type. Unlike field
strings, which extend only 'horizontally', internal tables also extend
'vertically'.

DATA OBJECTS
In ABAP/4, you can work with several kinds of data objects, such as:
· Internal data objects
· External data objects
· System-defined data objects
· Special data objects

Internal data objects
Internal data objects are created for use in one particular program. They
have no validity outside that program. Internal data objects include:
Literals
- Text literals (using type c)
Ex. Data name(10) type c value 'Maars soft'.
- Numeric literals (using type n)
Ex Data Pincode(10) type n value '600024'.
Variables
DATA: S1 TYPE I.
SUM = S1 + 10..
Constants
CONSTANTS PI TYPE P DECIMALS 10 VALUE '3.1415926536'.

External data objects
External data objects exist independently of programs.
ABAP/4 stores external data objects in tables defined in the ABAP/4
Dictionary. To access this data from within a program, you declare the
tables in the program with the TABLES statement .
System-defined data objects
Besides user-defined data objects, some data objects are defined
automatically by the system.
SY-UNAME : logon name of the user
SY-DATUM : current date
SY-UZEIT : current time

Special data objects
ABAP/4 also includes some data objects with special features, namely:
- Parameters
Parameters are variables which are linked to a selection screen. They can
accept values after a program is started.
- Selection criteria
Selection criteria are special internal tables used to specify value ranges.
They are also linked to a selection screen.

Basic Form of the DATA Statement
Syntax
DATA <f>[(<length>)] <type> [<value>] [<decimals>].
In its basic form, the keyword DATA has the following parameters:
<f> Naming a Variable
<length> <type> Specifying the Data Type and the Length of the
Variable
<value> Specifying a Start Value
<decimals> Specifying the Number of Digits after the Decimal
Point

Naming a Variable
The variable name <f> may be up to 30 characters long. You can use any
alphanumeric characters except those listed below.
· Do not use the following characters:
- plus sign +
- period .
- comma ,
- colon :
- parentheses ( )
· Do not create a name consisting entirely of numeric
characters.

Outputting Data to the Screen
Syntax
WRITE <f>.
Positioning WRITE Output on the Screen
Syntax
WRITE AT [/][<pos>][(<len>)] <f>.
Formatting Options
Syntax
WRITE .... <f> <option>.

Formatting options for all data types
LEFT-JUSTIFIED Output is left-justified.
CENTERED Output is centered.
RIGHT-JUSTIFIED Output is right-justified.
UNDER <g> Output starts directly under the field <g>.
NO-GAP The blank after the field <f> is omitted.
Formatting options for numeric fields
NO-SIGN The leading sign is not output.
DECIMALS <d> <d> defines the number of digits after the
decimal point.
EXPONENT <e> In type F fields, the exponent is defined in
<e>.

Outputting Symbols and Icons on the Screen
You can output symbols or R/3 icons on the screen by using the
following syntax:
Syntax
WRITE <symbol-name> AS SYMBOL.
WRITE <icon-name> AS ICON.
Ex.
INCLUDE <LIST>.
WRITE: / 'Phone Symbol:', SYM_PHONE AS SYMBOL.
SKIP.
WRITE: / 'Alarm Icon: ', ICON_ALARM AS ICON.

TEXT ELEMENTS
The ABAP/4 programming environment allows you to create and
maintain programs in several languages. You can store all texts the
program outputs to the screen as text elements in text pools.
Text elements comprise
· the title of the program.
· list headings and column headings for page headers of output
lists
· selection texts which appear on a selection screen
· text symbols which can be used in ABAP/4 statements instead of
literals.

Assigning values
In ABAP/4, you can assign values to data objects in both declarative and
operational statements.
To assign values to data objects in operational statements, you can use:
· the MOVE statement, which corresponds to the assignment
operator (=)
· the WRITE TO statement

The syntax for the MOVE statement is as follows:
MOVE <f1> TO <f2>.
The syntax for the assignment operator (=) is as follows:
<f2> = <f1>.
Example
DATA: NUMBER1 TYPE P DECIMALS 1 value '5.5'.
NUMBER2 TYPE P DECIMALS 1.
MOVE NUMBER1 TO NUMBER2.
(OR)
NUMBER2 = NUMBER1.
WRITE : 'NUMBER2 =' , NUMBER2.
The output will be: NUMBER2 = 5.5.

Basic Arithmetic Operations
ABAP/4 supports the four basic arithmetic operations, as well as power
calculation. You can specify the following arithmetic operators in a
mathematical expression:
+ Addition
- Subtraction
* Multiplication
/ Division
DIV Integer division
MOD Remainder of integer division
** Exponentiation

Controlling the Flow of an ABAP/4 Program
The flow of an ABAP/4 program can be controlled internally and
externally.
· The internal control is steered by standard keywords.
These keywords are
· for branching (IF, CASE)
· for looping (DO, WHILE)
· The external control is steered by events. Events are generated
either from other ABAP/4 programs (system programs or user programs)
or from interactive user input (like, for example, using the mouse to click
on the screen).

Conditional Branching using IF
The IF statement allows you to divert the program flow to a particular
statement block, depending on a condition. This statement block consists
of all the commands which occur between an IF statement and the next
ELSEIF, ELSE, or ENDIF statement.
Syntax
IF <condition1>.
<statement block>
ELSEIF <condition2>.
<statement block>
ELSEIF <condition3>.
<statement block>
.....
ELSE.
<statement block>
ENDIF.

Conditional Branching with CASE
To execute different statement blocks depending on the contents of
particular data fields, you use the CASE statement as follows:
Syntax
CASE <f>.
WHEN <f1>.
<statement block>
WHEN <f2>.
<statement block>
WHEN <f3>.
<statement block>
WHEN ...
......
WHEN OTHERS.
<statement block>

Unconditional Looping using DO
If you want to process a statement block more than once, you can
program a loop with the DO statement as follows:
Syntax
DO [<n> TIMES].
<statement block>
ENDDO.

Conditional Loops using WHILE
If you want to process a statement block more than once as long as a
condition is true, you can program a loop with the WHILE statement as
follows:
Syntax
WHILE <condition> .
<statement block>
ENDWHILE.

To terminate the processing of a loop, use one of the following keywords.
Keyword Purpose
CONTINUE Terminating a Loop Pass Unconditionally
CHECK Terminating a Loop Pass Conditionally
EXIT Terminating a Loop Entirely

Example for terminating a Loop Pass Unconditionally
To terminate a loop pass immediately without any condition, use the
CONTINUE statement as follows:
DO 4 TIMES.
IF SY-INDEX = 2.
CONTINUE.
ENDIF.
WRITE SY-INDEX.
ENDDO.
This produces the following output:
1 3 4
Here, the system terminates the second loop pass without processing the
WRITE statement.

Example for terminating a Loop Pass Conditionally
To terminate a loop pass conditionally, use the CHECK statement as
follows:
Syntax
CHECK <condition>.
DO 4 TIMES.
CHECK SY-INDEX BETWEEN 2 and 3.
WRITE SY-INDEX.
ENDDO.
2 3
Here, the system terminates the first and the fourth loop pass without
processing the WRITE statement because SY-INDEX does not fall
between 2 and 3.

Example for terminating a Loop Entirely
To terminate a loop entirely without any condition, use the EXIT
statement as follows:
Syntax
EXIT.
DO 4 TIMES.
IF SY-INDEX = 3.
EXIT.
ENDIF.
WRITE SY-INDEX.
ENDDO.
1 2
Here, the system terminates the entire loop processing in the third loop
pass without processing the WRITE statement or the fourth loop pass.

· Declarative keywords
These keywords define data types or declare the data
objects which the program can access. Examples of declarative
keywords are: TYPES, DATA, TABLES
· Control keywords
These keywords control the flow of an ABAP/4 program
according to certain conditions. Examples of control keywords are:
IF, WHILE, CASE
· Calling keywords
These keywords call processing blocks (defined by
modularization keywords) in the same or other ABAP/4 programs or
branch completely to other ABAP/4 programs. Examples of calling
keywords are: PERFORM, CALL, SUBMIT, LEAVE TO

Modularization keywords
These keywords define processing blocks in an ABAP/4 program.
Processing blocks are groups of statements which are processed during
the execution of an ABAP/4 program as soon as they are called from
another point.
Modularization keywords comprise:
* Event keywords
Example AT SELECTION SCREEN, START-OF-SELECTION
* Defining keywords
Example FORM, ENDFORM, FUNCTION, ENDFUNCTION.
Operational keywords
These keywords process the data (defined by declarative keywords)
when certain processing blocks (triggered by events or called by calling
keywords) are processed and certain conditions (defined by control
keywords) occur.
Examples of operational keywords are: WRITE, MOVE, ADD

There are three hierarchical levels of data types and objects:
* Program-independent data, defined in the ABAP/4 Dictionary
* Internal data used globally in one program
* Data used locally in a procedure (subroutine, function
module)
Data types in ABAP/4 are classified by structure and definition.
Data types are either:
· predefined or user-defined
· elementary (non structured) or structured

ABAP BASICs learn the basics of ABAP-1.ppt

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