Introduction ABAP Fields and Variables

1. Introduction ABAP Fields and Variables

2. Fields (Introduction) • In ABAP, fields (or data objects) are named locations in memory • Variables store data that might change • Constants store data that does not change • As before, fields are declared with the DATA keyword • KEEP IN MIND THAT ABAP IS A ‘BUSINESS’ PROGRAMMING LANGUAGE

3. Field Naming • Field names must begin with a letter or underscore character • Subsequent characters can be digits • 30 character maximum variable length • Avoid special characters • Don’t use anything but an underscore • Don’t use a dash for reasons you will discover shortly • Cannot be reserved words

4. Fields (Characteristics) • They nave a name • A defined length • And a data type • And possibly a length • And possibly an initial value

5. Fields (Primary Data Types)

6. Data Types and the ABAP Dictionary • ABAP data types and ABAP dictionary data types are not exactly the same • Dictionary types map to more simple ABAP types • See handout

7. Numeric Data Types (1) • Integer numbers are whole number having a value range between -2**31 to 2**31-1 • Results are rounded not truncated • Floating point numbers (data type F) are similar to IEEE floating point numbers • They are converted to a binary value and are subject to rounding error

8. Numeric Data Types (2) • Packed numbers (data type P) use an internal SAP format • The size is program defined between 1 and 16 bits • Each digit occupies 4 bits • So two decimal digits are packed into one byte • Up to 14 digits allowed after the decimal point • Make sure that fixed-point arithmetic is set. otherwise values are treated as integers • P fields are slow

9. Declaring Variables (1) • The DATA statement declares a variable • Syntax: • DATA VARNAME TYPE DATATYPE [VALUE INITIALVALUE]. • Example: • Declare an integer having an initial value of 5. DATA IntValue1 TYPE I VALUE 5.

10. Packed Numbers (Example) DATA packed16 TYPE P LENGTH 7 DECIMALS 2.packed16 = '12121219.12'.WRITE packed16. • Produces

11. LIKE • Declare a variable having the dame data type as another variable • Makes it easier to change data types DATA demo16instance1 LIKE packed16.DATA demo16instance2 LIKE packed16.

12. Arithmetic • Operators are as usual +, -, /, * • Use DIV for integer division and MOD for integer remainder • THERE MUST BE A BLANK CHARACTER BEFORE AND AFTER THE ‘=‘ SIGN AND BETWEEN ARITHMETIC OPERATORS AND PARENTHESIS

13. Arithmetic (Type Conversion) • Looks like any other arithmetic expression (plus the space requirements) • SAP calls this compatible and convertible data types • Compatible types have the same data type, field type, … • Comparable types are converted using conversion rules (See handout)

14. Type Coercion (1) • The following produces “1” because the result is rounded to an int

15. Type Coercion (2) • Floating point data (F, P) are rounded and converted to integers • Floating point numbers are rounded when converted to packed values • When converting character fields to numbers, the source field must contain a valid number • More about dates later

16. Numeric Overflow Outcome

17. System Fields • System fields are constants defined by the system • SY-SUBRC – return code of a procedure • SY-UNAME – logon name of the user • SY-DATUM – current date • SY-UZEIT – current type • SY-TCODE – current transaction code

18. Constants • The CONSTANTS statement declares a constant CONSTANTS pi TYPE P LENGTH 15 DECIMALS 14 VALUE '3.14159'.