Difference between Function Module and Subroutine in SAP ABAP

In SAP ABAP, the main difference between a function module and a subroutine lies in their reusability and visibility.

Function Module

A function module is a standalone unit of code that can be called from other programs or function modules. It can be executed independently and returns a value to the calling program.

Subroutine

A subroutine, on the other hand, is a part of a program and can only be called within the same program. It does not return any value and is primarily used for modularizing code within a program.

Key Differences:

• Function modules are standalone units of code that can be called from external programs, while subroutines are part of a program and can only be called internally.
• Function modules can return values to the calling program, whereas subroutines do not return any values.
• Function modules are more versatile and reusable compared to subroutines.