ABAP ALV has inbuilt functions to calculate totals and subtotals. If you want to calculate totals and subtotals programatically make use of field catalog and sort catalog.
To display logo in SAP ALV header, just pass the logo name in function module REUSE_ALV_COMMENTARY_WRITE.
To display header in ALV grid use the function module ‘REUSE_ALV_COMMENTARY_WRITE’ in TOP-OF-PAGE event.
The field catalog is a table which contains information on the fields to be displayed on the ALV output.
Subroutines are procedures that we define in an ABAP program and can be called from any program. Subroutines are normally called internally, i.e. called from the same program in which it is defined. But it is also possible to call a subroutine from an external program.
An ALV report is created using the standard function modules provided by SAP.
ALV stands for ABAP List Viewer. ALV gives us a standard List format and user interface to all our ABAP reports. ALV is created by a set of standard function modules provided by SAP.
Include programs allow you to use the same source code in different programs. They are mainly used for modularizing source code and have no parameter interface.
If we want to reuse the same set of statements more than once in a program, we can include them in a macro.
Modularization is breaking down a big program into smaller units, so that it is easy to maintain.