Sentinel Loops
Learn and practice loops controlled by a sentinel value.
We'll cover the following...
The sentinel value
Sometimes, the loop doesn’t have a fixed number of repetitions. Instead, an indicator value stops the loop. This special value is called the sentinel value. For example, we don’t know how much data is in a file without reading it all. However, we know that every file ends with an end-of-file (EOF) mark. So, the EOF mark is the sentinel value in this case.
Note: We should select a sentinel value that’s not expected in the normal input.
The while loop
We use the while loop when the termination of the loop depends on the sentinel value instead of a definite number of iterations.
As a simple example, we want to display the reverse sequence of digits in a positive integer value input by the user.
Remember: For some programs, once you run the program, it ...