Editing ABAP (section)

==Data types and variables==
ABAP provides a set of built-in data types. In addition, every structure, table, view or data element defined in the ABAP Dictionary can be used to type a variable. Also, object classes and interfaces can be used as types.
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The built-in data types are:
{| class="wikitable"
|-
! Type !! Description
|-
| I || Integer
|-
| P || Packed decimal
|-
| F || Floating point
|-
| N || Character numeric
|-
| C || Character
|-
| D || Date
|-
| T || Time
|-
| X || Hexadecimal (raw byte)
|-
| STRING || Variable-length string
|-
| XSTRING || Variable-length raw byte array
|}
Date variables or constants (type D) contain the number of days since January 1, 1 AD. Time variables or constants (type T) contain the number of seconds since midnight. A special characteristic of both types is that they can be accessed both as integers and as character strings (with internal format "YYYYMMDD" for dates and "hhmmss" for times), which can be used for date and time handling. For example, the code snippet below calculates the last day of the previous month (note: SY-DATUM is a system-defined variable containing the current date):
<syntaxhighlight lang="abap">
DATA LAST_EOM    TYPE D.  "last end-of-month date

* Start from today's date
  LAST_EOM = SY-DATUM.
* Set characters 6 and 7 (0-relative) of the YYYYMMDD string to "01",
* giving the first day of the current month
  LAST_EOM+6(2) = '01'.
* Subtract one day
  LAST_EOM = LAST_EOM - 1.

  WRITE: 'Last day of previous month was', LAST_EOM.
</syntaxhighlight>
All ABAP variables have to be explicitly [[Declaration (computer science)|declared]] in order to be used. They can be declared either with individual statements and explicit typing or, since ABAP 7.40, inline with [[type inference|inferred typing]].

=== Explicitly typed declaration ===
Normally all declarations are placed at the top of the code module (program, subroutine, function) before the first executable statement; this placement is a convention and not an enforced syntax rule.  The declaration consists of the name, type, length (where applicable), additional modifiers (e.g. the number of implied decimals for a packed decimal field) and optionally an initial value:
<syntaxhighlight lang="abap">
* Primitive types:
DATA: COUNTER      TYPE I,
      VALIDITY     TYPE I VALUE 60,
      TAXRATE(3)   TYPE P DECIMALS 1,
      LASTNAME(20) TYPE C,
      DESCRIPTION  TYPE STRING.

* Dictionary types:
DATA: ORIGIN       TYPE COUNTRY.

* Internal table:
DATA: T_FLIGHTS    TYPE TABLE OF FLIGHTINFO,
      T_LOOKUP     TYPE HASHED TABLE OF FLT_LOOKUP.

* Objects:
DATA: BOOKING      TYPE REF TO CL_FLT_BOOKING.
</syntaxhighlight>
Notice the use of the colon to chain together consecutive DATA statements.

=== Inline declaration ===
Since ABAP 7.40,<ref>{{Cite web |title=DATA - Inline Declaration |url=https://help.sap.com/doc/abapdocu_751_index_htm/7.51/en-US/abendata_inline.htm |website=help.sap.com}}</ref> variables can be  declared inline with the following syntax:
<syntaxhighlight lang="abap">
DATA(variable_name) = 'VALUE'.
</syntaxhighlight>

For this type of declaration it must be possible to infer the type statically, e.g. by [[method signature]] or database table structure.

This syntax is also possible in OpenSQL statements:
<syntaxhighlight lang="abap">
SELECT * FROM ekko into @DATA(lt_ekko) WHERE ebeln EQ @lv_ebeln.
</syntaxhighlight>