This question already has answers here:
Does Python support short-circuiting?
(3 answers)
Closed 3 years ago.
I am curious if Python will continue checking conditions in an if statement if the first condition returns False. I'm wondering about this because I want to know if best practice is try to check conditions with low time-complexity before more complex checks.
Is there any difference between these two snippets?
if condition_1() and condition_2():
do_something()
and
if condition_1():
if condition_2():
do_something()
Yes, python boolean operators do short-circuit
Both code samples are semantically equivalent, but the first is more readable, as it has lower level of nesting.
Related
This question already has answers here:
Python 2.7 Boolean Operators Logic
(1 answer)
How does boolean operator work on string in python
(6 answers)
Closed 2 years ago.
I have a very basic snippet of code.
print("a" or "b")
>> a
I'm not entirely sure what I expected to happen.
Why does this print "a", and in general how are strings handled with python control flow?
In python, empty strings evaluate to False in a boolean context, while non-empty strings are True.
This question already has answers here:
How to test multiple variables for equality against a single value?
(31 answers)
Closed 2 years ago.
Generally, there are two variations of writing repeated if conditions that I know of:
Simple
if x != <something> and x != <somethingElse> and x != <somethingElse +>:
Little compact
if all(x != el for el in [<something>, <somethingElse>, <somethingElse +>]
Is there a more compact way?
For x should not be in a group of things, the easiest solution is just:
if x not in (<something>, <somethingElse>, <somethingElse +>):
Expanding it for more items adds little verbosity, and it's relatively efficient, assuming the cost of computing each of the somethings is small (it has to compute them all up front, but then, so does anything aside from one by one comparisons or complicated solutions involving programmatically generatable somethings).
This question already has answers here:
How can I get the next string, in alphanumeric ordering, in Python?
(4 answers)
Closed 6 years ago.
If Python has an implementation of Ruby's next method? I mean something what works exactly the same as in Ruby, so if I type e.g. "z".next it will return "aa" (instead of just next sign in ascii table), "az".next will return "ba" and so on.
I don't believe there is a built-in method for this in Python. A similar question was asked on How can I get the next string, in alphanumeric ordering, in Python? and the accepted answer gives a solution.
This question already has answers here:
Is there a difference between "==" and "is"?
(13 answers)
Closed 7 years ago.
I was reading from the book How to Think Like A Computer Scientist: Learning with Python when I came across the following question:
As an exercise, describe the relationship between string.join(string.split(song)) and song. Are they the same for all strings? When would they be different?
(song had been defined as "The rain in Spain...")
After checking it out, however, I found that both are different strings. I tried using string.join(string.split(song)) is song and f is song where f had been assigned the value string.join(string.split(song)) and both evaluated to False. Why is it so?
What are the actual values of the strings you are comparing?
If both are the same, this is because of the difference between the identity operator is and the equality operator ==.
In short, is yields True when objects are identical. Because a new string is created in your example, it produces False.
If you'd use == a deep comparison of the strings' characters would take place and True would be returned.
If the compared strings are not the same, neither == or is should produce True.
This question already has answers here:
How to test multiple variables for equality against a single value?
(31 answers)
Closed 8 years ago.
I am new in Python and I try to sense the difference between two expression.
Is that:
a=1
if a==0 or 1:
print (a)
is same as:
a=1
if a==0 or a==1:
print(a)
Try using == instead of =. = is an assignment operator whereas == checks if the two are equal. Also, the first bit of code is not correct. You have to rewrite the entire condition.