 Here's the flowchart for a program that asks the user for their age and years and then tells them their approximate age and days and Here's the code There's nothing wrong with it Except that every time we want another age we have to run the program again and Again What we'd really like is to run the program once and have it ask us over and over again for an age This is a perfect use for a while loop. Here's a revised flowchart Ask for an age and then test a condition as long as the condition is true Process the age ask for the next age and Loop back to see if the program should continue or not the question now becomes what's a good condition to test We need some value for the age that will tell the program. Okay. I'm finished This value is called a sentinel value It's a special value that doesn't represent valid data But instead tells the while loop that it's time to stop in this case. The sentinel value is zero It's a good sentinel people don't usually think of zero as a normal age So we can use that as our special okay. We're finished value This means the loop continues as long as the age is not zero Let's update the code to match this flowchart First change the description of what the program does Do this until the user gives us a zero for the age in years Next we'll add something to the prompt enter age in years or zero to quit Now we're going to add our while loop As long as the years is not equal to zero We'll put in the closing brace for the loop and indent the loop body After processing the age add code to ask for another age Enter another age in years or zero to quit and a scan F build and run and Now we can enter ages to our heart's content And when we're finished we enter zero and that ends our program and That's how you can use a loop to repeatedly ask for user input