Is there an order of operations for control flow? Like does the and come before the multiplication or is there an order for and, or, not, etc. ?
Logical operators have operator precedence the same as other operators (relational, arithmetic, etc.). The highest precedence belongs to
not, followed by
and, and finally by
Like other operations, grouping takes precedence, so we must evaluate bracketed expressions first, if they exist.
Excuse me but how this operator precedence can be useful? What are some examples of using it actually?
Thank you in advance.
print(True or False and False) # and has precedence print((True or False) and False) # parentheses change precedence print(not False or True) # not has precedence print(not (False or True)) # parentheses change precedence
True False True False
Thank you very much. Each time one of my questions is answered i get that "Ooooh now i get it " feeling!!!
Hello, would you explain to me why it prints only one statement?
If you’re referring to the order of operations performed by @patrickd314, then only output is gained after evaluating through the input expressions. So for example,
print (not False or True)
Not False is evaluated first to become “not False” aka True. After that the
oroperator takes two True values to output a single outcome of
Hope that answers your question!
Yes, i understand it now, thank you. But for me the first part of
print(True or False and False) # and has precedence print((True or False) and False) # parentheses change precedence
was more confusing.
It wasn’t obvious a little that these are not just expressions but parts that require certain answers to be “True” or “False”. For example:
“True and True” is True but “True and False” is False.
So expression with “and” needs to be only “True and True” to be True. And expression with “or” only requires one element to be “True” for it to be True.
In my experience at first i just looked at them as simple comparisons similar to what you can find in math and you just need to solve them. So i thought that “False and False” had to be “True” expression )
Gotcha. Yep, I was confused on this just like you mentioned for like the longest time until I briefly went through the introduction to logic course offered free from stanford:
I did not finish the whole thing as the thing becomes very theoretical and very complex towards the end, but covered enough to understand how the boolean operators work within logic. It’s a pretty good course to check out in general!
Wow, thank you very much!
Good question. Was wondering the same thing.
Thanks, for sharing.
well personally when i first saw i compared to what I know in math. Being that “and” has precedence. In the first expression “False and False” had to be answered first which is True and what’s left to process would be “True or True” which is True. In the second expression, parentheses has precedence so “True or False” would be answered first which is “True” and then “True and False”, which will answer “False”.
Yeah… but you did the same mistake as i did )
False and False = “False”, not “True”.
That’s what i was talking about, mathematical approach ))
For the second expression, why would “True or False” be evaluated to True and not False? Since it is an or statement, won’t the system have a 50/50 chance of evaluating it to either True or False?
Ahh I just moved on to the next lesson and it mentions that an or statement requires only one component to be True for the entire statement tp be True. Hence, True or False is evaluated as True.