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If you have an if statement where several variables or functions are evaluated, in which order are they evaluated?
if foo > 5 or bar > 6: print 'foobar' In this specific case, will foo be evaluated against the five and then bar against the 6 (left to right) or will it be evaluated right to left? I am assuming that a or and and is evaluated in the same order.
800
Yes, the order of the conditions matters. In your code, you test if(a==b) first. If all 3 integers are the same, then this will be true and only return c; will execute. It won't even bother with the rest of the conditions.
In Python, the left operand is always evaluated before the right operand. That also applies to function arguments. Python uses short circuiting when evaluating expressions involving the and or or operators.
The left clause will be evaluated first, and then the right one only if the first one is False.
This is why you can do stuff like:
if not person or person.name == 'Bob': print "You have to select a person and it can't be Bob" Without it breaking.
Conversely, with an and clause, the right clause will only be evaluated if the first one is True:
if person and person.name: # ... Otherwise an exception would be thrown when person is None.
95
It will be evaluated left to right.
>>> def a(): ... print 'a' ... return False ... >>> def b(): ... print 'b' ... return False ... >>> print a() or b() a b False >>> def c(): ... print 'c' ... return True ... >>> print c() or a() c True If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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