Sentinel value

So, think of a sentinel value like a special code that you use to show something is finished or not there. It's like saying "hey, I'm done here" or "there's nothing more to see." It's like a secret signal that tells a computer program or other system to stop doing something or to move onto the next thing.

For example, let's say you're playing a game of hide-and-seek and you use the word "banana" to signal that you give up and are done hiding. Banana is the sentinel value in this case. When someone hears you say "banana," they know the game is over and it's time to start a new one.

In a computer program, a sentinel value is often used to tell the program when to stop reading or processing data. Let's say we have a program that reads a list of numbers and calculates the average. We might use a sentinel value of "-1" to tell the program that there are no more numbers to read and it's time to calculate the average. The program would keep reading numbers until it sees the sentinel value of "-1" and then it would know to stop.

Overall, a sentinel value is like a secret code that signals the end of something or tells a program what to do next.