Overview of ABAP Programming Basics

Overview of ABAP Programming Basics

ABAP Syntax

The syntax of the ABAP programming language contains of ABAP statements and comments.

ABAP Statements Normally, each ABAP statement begins with a keyword.

A statement consist operands and additions of the keyword and is always ended with a period.

You can enter statements in any format, so a statement can be indented, you can write several statements on one line, or spread a single statement over several lines.

Chained Statements The ABAP programming language allows you to concatenate consecutive statements with an identical first part into a chain statement.

To do this, you write the identical part for all statements only once and place a colon after it.

You could, for example, write the same statement like this:
WRITE: vbak-vbeln,
vbak-cityto,
vbak-airpto.

Data Types and Data Objects Programs work with local program data - that is, with byte sequences in the working memory.

Byte sequences that belong together are called fields and are characterized by a length, an identity, and - as a further attribute - by a data type.

There are separate name spaces for data objects and data types.

Data Types As well as occurring as attributes of a data object, data types can also be defined independently.

Data Objects Data objects are the physical units with which ABAP statements work at runtime.

ABAP statements access these contents by addressing the name of the data object and interpret them according to the data type.

Statements can write the contents of data objects in lists or in the database, they can pass them to and receive them from routines, they can change them by assigning new values, and they can compare them in logical expressions. Executing ABAP Program Units ABAP programs can be executed only on a NetWeaver Application Server ABAP. The NetWeaver Application Server ABAP contains a component Kernel & Management Services, which serves as the platform-independent run time environment for ABAP programs.

Each ABAP program has a program type, which determines whether and how a program can be run.

A logical database contains subroutines that are called by an invisible system program in a prescribed sequence for executable programs.

Subroutine Pools Subroutine pools are container programs for subroutines that should only be called externally.

They are used exclusively for modularizing ABAP source code, and are included in other programs.

Note As of release 6.10, function groups, class pools and subroutine pools can be started via transaction codes, which are attached to the public methods of local or global classes of these programs.

Starting Programs in ABAP for all programs that can be started directly; there are ABAP statements that you can use to call a program from another application program that is already running.