How to do sentinel logic

Here is the pattern: (note this is NOT code!)

    input statement (inputting into a variable x)

    while x is not the sentinel value
       process x as needed
       input statement (inputting into a variable x) 
		(yes, this is the same statement as the one outside of the loop!)

Summary

• input before the loop
• test at the top of the loop for the value
  • do not read more into the spec than it says, "a -1" is NOT the same thing as "anything negative"!
• process the data inside the loop - you know it is valid data
• at the very bottom of the loop do another input, just like the one before the loop starts