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Using not to Determine Range
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Here’s another example of when you might use not in an if statement condition. Determining if a number is inside or outside a particular range of values is a very common task.
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And writing a condition to see if a number is inside a range is pretty straightforward. You usually use a compound inequality using the word and. To be in the range 20 to 40, including the end point of 20, a number has to be at least 20 and at the same time, less than 40.
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And 30 is indeed inside that range. This type of comparison is so common that there are other ways to write this condition. And you’ll see at least one of those in an upcoming lesson.
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But now suppose you want to check if a number is outside that range. What would that condition look like? Well, the easiest way is to just put not in front of this condition.
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If you say not followed by the previous condition, this will now be True when a number is outside of that range. Remember you want to do the and first, so that part of the condition has to be put in parentheses.
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And 50 is outside of that range. Next, you’ll see how not can be used in the condition for while loops.
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