ABAP provides a set of predefined functions. A predefined function calculates a return value from an argument. A predefined function can be used on an operand position as follows:
... func( arg ) ...
In this case, func is the predefined function and the argument arg is a data object with an appropriate data type for the function. If a predefined function is used at an operand position, the function is executed before the operand is used, and the return value of the predefined function is used as an operand according to its data type.
Before release 6.10, predefined functions could only be used as operands in arithmetic expressions of the statement COMPUTE.
As of release 6.10, predefined functions can also be used as a source field for the statement MOVE, as operands in logical expressions, as operands of the statements CASE and WHEN, or as operands of the additions WHERE in the statements LOOP AT, DELETE, and MODIFY for internal tables.
Predefined functions are classifed into