Variable Number of Repetitions:A variable number of repetitions refers to a loop structure where the number of iterations is determined by a condition that can change during runtime.
End-of-file (EOF): EOF is another way to mark the end of data input in programming, often used when reading files or streams.
Null Value: In some cases, null values are used as sentinels in databases or programming languages. They represent missing or unknown values and help indicate when data processing should stop.