Python “in” and “==” confusion
print('a' in 'aa')
print('a' in 'aa' == True)
print(('a' in 'aa') == True)
print('a' in ('aa' == True))
The output is
True
False
True
Traceback (most recent call last):
File "main.py", line 6, in <module>
print('a' in ('aa' == True))
TypeError: argument of type 'bool' is not iterable
If line 2 is neither line 3 nor line 4, then what is it? How does it get False?
python
asked Nov 21 '18 at 18:13
petepete
7262827
|
show 3 more comments
print('a' in 'aa')
print('a' in 'aa' == True)
print(('a' in 'aa') == True)
print('a' in ('aa' == True))
The output is
True
False
True
Traceback (most recent call last):
File "main.py", line 6, in <module>
print('a' in ('aa' == True))
TypeError: argument of type 'bool' is not iterable
If line 2 is neither line 3 nor line 4, then what is it? How does it get False?
python
asked Nov 21 '18 at 18:13
petepete
7262827
@PatrickArtner I'm finding it unusually difficult to find the canonical I'm thinking of. It's due to chaining but I can't find the link :/
– roganjosh
Nov 21 '18 at 18:23
That's the one you originally flagged with but I'm sure there is a canonical. Where is it?! :P
– roganjosh
Nov 21 '18 at 18:25
@roganjosh this here? stackoverflow.com/questions/6074018/…
– Patrick Artner
Nov 21 '18 at 18:27
1
@PatrickArtner it got hammered and they presumably decided to reverse that, but now it shows no close votes to me.
– roganjosh
Nov 21 '18 at 18:42
1
@PatrickArtner i saw timgeb as the second closer. It must be a hammer. I'm not sure how to view that history, though.
– roganjosh
Nov 21 '18 at 18:46
|
show 3 more comments
print('a' in 'aa')
print('a' in 'aa' == True)
print(('a' in 'aa') == True)
print('a' in ('aa' == True))
The output is
True
False
True
Traceback (most recent call last):
File "main.py", line 6, in <module>
print('a' in ('aa' == True))
TypeError: argument of type 'bool' is not iterable
If line 2 is neither line 3 nor line 4, then what is it? How does it get False?
python
asked Nov 21 '18 at 18:13
petepete
7262827
print('a' in 'aa')
print('a' in 'aa' == True)
print(('a' in 'aa') == True)
print('a' in ('aa' == True))
The output is
True
False
True
Traceback (most recent call last):
File "main.py", line 6, in <module>
print('a' in ('aa' == True))
TypeError: argument of type 'bool' is not iterable
If line 2 is neither line 3 nor line 4, then what is it? How does it get False?
python
python
asked Nov 21 '18 at 18:13
petepete
7262827
asked Nov 21 '18 at 18:13
petepete
7262827
asked Nov 21 '18 at 18:13
petepete
7262827
asked Nov 21 '18 at 18:13
petepete
7262827
asked Nov 21 '18 at 18:13
petepete
7262827
7262827
@PatrickArtner I'm finding it unusually difficult to find the canonical I'm thinking of. It's due to chaining but I can't find the link :/
– roganjosh
Nov 21 '18 at 18:23
That's the one you originally flagged with but I'm sure there is a canonical. Where is it?! :P
– roganjosh
Nov 21 '18 at 18:25
@roganjosh this here? stackoverflow.com/questions/6074018/…
– Patrick Artner
Nov 21 '18 at 18:27
1
@PatrickArtner it got hammered and they presumably decided to reverse that, but now it shows no close votes to me.
– roganjosh
Nov 21 '18 at 18:42
1
@PatrickArtner i saw timgeb as the second closer. It must be a hammer. I'm not sure how to view that history, though.
– roganjosh
Nov 21 '18 at 18:46
|
show 3 more comments
@PatrickArtner I'm finding it unusually difficult to find the canonical I'm thinking of. It's due to chaining but I can't find the link :/
– roganjosh
Nov 21 '18 at 18:23
That's the one you originally flagged with but I'm sure there is a canonical. Where is it?! :P
– roganjosh
Nov 21 '18 at 18:25
@roganjosh this here? stackoverflow.com/questions/6074018/…
– Patrick Artner
Nov 21 '18 at 18:27
1
@PatrickArtner it got hammered and they presumably decided to reverse that, but now it shows no close votes to me.
– roganjosh
Nov 21 '18 at 18:42
1
@PatrickArtner i saw timgeb as the second closer. It must be a hammer. I'm not sure how to view that history, though.
– roganjosh
Nov 21 '18 at 18:46
@PatrickArtner I'm finding it unusually difficult to find the canonical I'm thinking of. It's due to chaining but I can't find the link :/
– roganjosh
Nov 21 '18 at 18:23
@PatrickArtner I'm finding it unusually difficult to find the canonical I'm thinking of. It's due to chaining but I can't find the link :/
– roganjosh
Nov 21 '18 at 18:23
That's the one you originally flagged with but I'm sure there is a canonical. Where is it?! :P
– roganjosh
Nov 21 '18 at 18:25
That's the one you originally flagged with but I'm sure there is a canonical. Where is it?! :P
– roganjosh
Nov 21 '18 at 18:25
@roganjosh this here? stackoverflow.com/questions/6074018/…
– Patrick Artner
Nov 21 '18 at 18:27
@roganjosh this here? stackoverflow.com/questions/6074018/…
– Patrick Artner
Nov 21 '18 at 18:27
1
1
@PatrickArtner it got hammered and they presumably decided to reverse that, but now it shows no close votes to me.
– roganjosh
Nov 21 '18 at 18:42
@PatrickArtner it got hammered and they presumably decided to reverse that, but now it shows no close votes to me.
– roganjosh
Nov 21 '18 at 18:42
1
1
@PatrickArtner i saw timgeb as the second closer. It must be a hammer. I'm not sure how to view that history, though.
– roganjosh
Nov 21 '18 at 18:46
@PatrickArtner i saw timgeb as the second closer. It must be a hammer. I'm not sure how to view that history, though.
– roganjosh
Nov 21 '18 at 18:46
|
show 3 more comments
2 Answers
2
active
oldest
votes
According to Expressions
print('a' in 'aa' == True)
is evaluated as
'a' in 'aa' and 'aa' == True
which is False.
See
print("a" in "aa" and "aa" == True)
==> False
The rest is trivial - it helps to keep operator precedence in mind to figure them out.
Similar ones:
- Multiple comparison operators in single statement
- Why does the expression 0 < 0 == 0 return False in Python?
with different statements. I flagged for dupe but the UI is wonky - I answered non the less to explain why yours exactly printed what it did.
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
add a comment |
Case 1 : it's simple the answers is True.
print('a' in 'aa')
Case 2 : This operation is evaluated as 'a' in 'aa' and 'aa' == True, so obviously it will return false.
print('a' in 'aa' == True)
Case 3: Now because we have () enclosing ('a' in 'aa') and the precedence of () is highest among all so first 'a' in 'aa' is evaluated as True and then True == True
print(('a' in 'aa') == True)
Case 4 : Same as above because of precedence of (), its evaluated as 'aa' == True, which will result in error as it tries to apply in on a non iterable that is bool value.
print('a' in ('aa' == True))
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
1
comparing a string with a bool is perfectly fine - the error is trying to useinon a non iterable bool type ...
– Patrick Artner
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
According to Expressions
print('a' in 'aa' == True)
is evaluated as
'a' in 'aa' and 'aa' == True
which is False.
See
print("a" in "aa" and "aa" == True)
==> False
The rest is trivial - it helps to keep operator precedence in mind to figure them out.
Similar ones:
- Multiple comparison operators in single statement
- Why does the expression 0 < 0 == 0 return False in Python?
with different statements. I flagged for dupe but the UI is wonky - I answered non the less to explain why yours exactly printed what it did.
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
add a comment |
According to Expressions
print('a' in 'aa' == True)
is evaluated as
'a' in 'aa' and 'aa' == True
which is False.
See
print("a" in "aa" and "aa" == True)
==> False
The rest is trivial - it helps to keep operator precedence in mind to figure them out.
Similar ones:
- Multiple comparison operators in single statement
- Why does the expression 0 < 0 == 0 return False in Python?
with different statements. I flagged for dupe but the UI is wonky - I answered non the less to explain why yours exactly printed what it did.
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
add a comment |
According to Expressions
print('a' in 'aa' == True)
is evaluated as
'a' in 'aa' and 'aa' == True
which is False.
See
print("a" in "aa" and "aa" == True)
==> False
The rest is trivial - it helps to keep operator precedence in mind to figure them out.
Similar ones:
- Multiple comparison operators in single statement
- Why does the expression 0 < 0 == 0 return False in Python?
with different statements. I flagged for dupe but the UI is wonky - I answered non the less to explain why yours exactly printed what it did.
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
According to Expressions
print('a' in 'aa' == True)
is evaluated as
'a' in 'aa' and 'aa' == True
which is False.
See
print("a" in "aa" and "aa" == True)
==> False
The rest is trivial - it helps to keep operator precedence in mind to figure them out.
Similar ones:
- Multiple comparison operators in single statement
- Why does the expression 0 < 0 == 0 return False in Python?
with different statements. I flagged for dupe but the UI is wonky - I answered non the less to explain why yours exactly printed what it did.
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
edited Nov 21 '18 at 18:42
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
answered Nov 21 '18 at 18:23
Patrick ArtnerPatrick Artner
22.7k62243
22.7k62243
add a comment |
add a comment |
Case 1 : it's simple the answers is True.
print('a' in 'aa')
Case 2 : This operation is evaluated as 'a' in 'aa' and 'aa' == True, so obviously it will return false.
print('a' in 'aa' == True)
Case 3: Now because we have () enclosing ('a' in 'aa') and the precedence of () is highest among all so first 'a' in 'aa' is evaluated as True and then True == True
print(('a' in 'aa') == True)
Case 4 : Same as above because of precedence of (), its evaluated as 'aa' == True, which will result in error as it tries to apply in on a non iterable that is bool value.
print('a' in ('aa' == True))
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
1
comparing a string with a bool is perfectly fine - the error is trying to useinon a non iterable bool type ...
– Patrick Artner
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
add a comment |
Case 1 : it's simple the answers is True.
print('a' in 'aa')
Case 2 : This operation is evaluated as 'a' in 'aa' and 'aa' == True, so obviously it will return false.
print('a' in 'aa' == True)
Case 3: Now because we have () enclosing ('a' in 'aa') and the precedence of () is highest among all so first 'a' in 'aa' is evaluated as True and then True == True
print(('a' in 'aa') == True)
Case 4 : Same as above because of precedence of (), its evaluated as 'aa' == True, which will result in error as it tries to apply in on a non iterable that is bool value.
print('a' in ('aa' == True))
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
1
comparing a string with a bool is perfectly fine - the error is trying to useinon a non iterable bool type ...
– Patrick Artner
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
add a comment |
Case 1 : it's simple the answers is True.
print('a' in 'aa')
Case 2 : This operation is evaluated as 'a' in 'aa' and 'aa' == True, so obviously it will return false.
print('a' in 'aa' == True)
Case 3: Now because we have () enclosing ('a' in 'aa') and the precedence of () is highest among all so first 'a' in 'aa' is evaluated as True and then True == True
print(('a' in 'aa') == True)
Case 4 : Same as above because of precedence of (), its evaluated as 'aa' == True, which will result in error as it tries to apply in on a non iterable that is bool value.
print('a' in ('aa' == True))
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
Case 1 : it's simple the answers is True.
print('a' in 'aa')
Case 2 : This operation is evaluated as 'a' in 'aa' and 'aa' == True, so obviously it will return false.
print('a' in 'aa' == True)
Case 3: Now because we have () enclosing ('a' in 'aa') and the precedence of () is highest among all so first 'a' in 'aa' is evaluated as True and then True == True
print(('a' in 'aa') == True)
Case 4 : Same as above because of precedence of (), its evaluated as 'aa' == True, which will result in error as it tries to apply in on a non iterable that is bool value.
print('a' in ('aa' == True))
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
edited Nov 21 '18 at 18:35
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
answered Nov 21 '18 at 18:31
Sanchit KumarSanchit Kumar
34319
34319
1
comparing a string with a bool is perfectly fine - the error is trying to useinon a non iterable bool type ...
– Patrick Artner
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
add a comment |
1
comparing a string with a bool is perfectly fine - the error is trying to useinon a non iterable bool type ...
– Patrick Artner
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
1
1
comparing a string with a bool is perfectly fine - the error is trying to use
in on a non iterable bool type ...– Patrick Artner
Nov 21 '18 at 18:32
comparing a string with a bool is perfectly fine - the error is trying to use
in on a non iterable bool type ...– Patrick Artner
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
Comparing a string to a Boolean does not throw an error.
– roganjosh
Nov 21 '18 at 18:32
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
My bad, I put it in wrong words.
– Sanchit Kumar
Nov 21 '18 at 18:33
add a comment |
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@PatrickArtner I'm finding it unusually difficult to find the canonical I'm thinking of. It's due to chaining but I can't find the link :/
– roganjosh
Nov 21 '18 at 18:23
That's the one you originally flagged with but I'm sure there is a canonical. Where is it?! :P
– roganjosh
Nov 21 '18 at 18:25
@roganjosh this here? stackoverflow.com/questions/6074018/…
– Patrick Artner
Nov 21 '18 at 18:27
1
@PatrickArtner it got hammered and they presumably decided to reverse that, but now it shows no close votes to me.
– roganjosh
Nov 21 '18 at 18:42
1
@PatrickArtner i saw timgeb as the second closer. It must be a hammer. I'm not sure how to view that history, though.
– roganjosh
Nov 21 '18 at 18:46