91download.com supports a wide range of platforms, including YouTube, Facebook, Twitter, TikTok, Instagram, Dailymotion, Reddit, Bilibili, Douyin, Xiaohongshu and Zhihu, etc. Click the download button below to parse and download the current video
Have you ever wondered how a computer decides whether a song belongs on your playlist or not? The answer lies in the realm of Boolean logic, a fundamental concept that governs how computers evaluate expressions using logical operators. Let's delve into the order of operations for compound Boolean expressions and uncover the secrets behind these evaluations.
Imagine you're crafting a program to filter songs based on specific criteria. You might encounter an expression like this: "Are the song's beats per minute (BPM) both greater than or equal to 150 and less than or equal to 180?" What happens when you feed this into the computer? The logical operators, such as 'and', come last in the order of operations, but how does the computer handle the evaluation?
The computer first evaluates the two sides of the expression separately. Suppose the variable 'BPM' holds the value 200. The comparison operators—greater than or equal to and less than or equal to—have equal precedence, so the computer assesses them from left to right. By substituting 200 into the left-hand side, we find that 200 is indeed greater than or equal to 150, resulting in true. However, on the right-hand side, 200 is not less than or equal to 180, which evaluates to false.
Now, with both sides simplified to Boolean values, the computer assesses the 'and' operator. Remember, an 'and' expression is only true if both sides are true. Therefore, a true 'and' a false yields false. And just like that, the computer arrives at its conclusion.
But what happens when you have an expression with multiple logical operators? Consider this scenario: "Is the genre any of the spellings of lo-fi?" If the variable 'genre' contains the string 'lo-fi', the computer evaluates the expressions around the logical operators before applying the 'ors'. It starts with the leftmost expression, moves to the second, and finally the third. If one of these expressions evaluates to true, the entire 'or' expression will also be true, thanks to short circuit evaluation—a clever optimization that stops further evaluation once the outcome is known.
Understanding short circuit evaluation can help you avoid runtime errors. For instance, if the variable 'group size' contains zero, attempting to divide by zero would lead to a runtime error. However, by checking if 'group size' equals zero first, you can leverage short circuit evaluation to skip the division and avoid the error.
Lastly, let's discuss the 'not' operator, which takes precedence over 'and' and 'or'. While it's essential to use 'not' sparingly to maintain readability, it can be a powerful tool when needed. For example, the expression "Is the genre not equal to rock and is the BPM greater than 130?" is clearer without the 'not' applied to the entire expression. Overusing 'not' can lead to confusion, much like saying "I prefer not blue colors" or "I'm going to not not in this video now."
In conclusion, Boolean logic is the bedrock of decision-making in computing. By understanding how computers evaluate expressions and utilize short circuit evaluation, you can craft more efficient and error-free programs. So, the next time you're pondering whether a song belongs on your playlist, remember the intricate dance of logical operators that makes it all possible.
Share on Twitter Share on Facebook