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Chapter 13. Validating and Formatting Data > THE LOGIC BEHIND VALIDATING DATA

THE LOGIC BEHIND VALIDATING DATA

Every day we validate things—from words in a sentence (to make sure they make sense) to change received from purchases. Thus, the concept is a natural and easy one for us to understand. Take the following phone number: 555-34567

Chances are, you quickly recognized the above phone number to be invalid. How? Your brain analyzed the phone number and noted that it contained eight numbers. After comparing this fact to the rule that defines valid local phone numbers as those that include seven numbers, your brain made a determination of true (the number was valid) or false (it was invalid). If you determine that the above number is valid, you can place the phone call. If, however, the number is invalid, your brain will log an error message—something like “That number is wrong. I need to get the correct number and then try to call.”


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