Like other higher programming languages, ABAP/4 provides standard keywords to control the flow of a program.
Usually ABAP/4 programs get executed statement by statement. Many times you need to skip few statements depending upon certain conditions i.e., you change the flow of program. This can be done by:
• branching (IF, CASE)
• looping (DO, WHILE)
However, unlike other language where you have only internal control, ABAP/4 has internal control and external control of the program flow.
• The internal control is steered by standard keywords as mentioned above. You define this in your program code.
• The external control is stored by events. Events are generated either from other ABAP/4 programs or from interactive user input (like, for example, using the mouse to click on the screen). The system does not necessarily process the statements in the same sequence as they are listed in an ABAP/4 program. This makes ABAP/4 an event-driven programming language. The external control plays an important role mainly for report programs.
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