Alignment of Data Objects (SAP Library - ABAP Programming (BC-ABA))

Alignment of Data Objects

Elementary fields with types I and F occupy special memory addresses that are platform-specific. For example, the address of a type I field must be divisible by 4, and the address of a type F field by 8. Consequently, type I and F fields are known as aligned fields. Structures containing fields with type I or F are also aligned, and may contain filler fields immediately before their aligned components.

The system normally aligns fields and structures automatically when you declare them.

You must take alignment into account in the following cases:

When you pass elementary fields or structures to a procedure as actual parameters where the corresponding formal parameter is not typed accordingly.

When you declare field symbols

When you use a work area with an ABAP Open SQL statement that does not have the same type as the database table as defined in the ABAP Dictionary.

When you process components of structures.