Hi all
python 2.7
can someone explain the logic here I am confused
(doesn't take much to confuse me
In the first example everything works OK.But the second example despite the fact that x is a variable
it doesn't work.Now the question here is this...does python have strange logic...or do I
example 1
a = 1
print a
a +=1
print a
example 2
e = 10
print e
x = e +=1
print x
kind regards
al
In example 2, line 3
x = e +=1
rise SyntaxError: Invalid syntax (of course).
What you expect this line to do?
(May-03-2017, 10:34 AM)idontreallywolf Wrote: [ -> ]because x = e += 1 is same as
x = e = e + 1
actually, the first one is invalid syntax and rise SynatxError,
while second one is perfectly fine
e = 10
x = e = e + 1
print x
print e
Output:
11
11
(May-03-2017, 10:39 AM)buran Wrote: [ -> ] (May-03-2017, 10:34 AM)idontreallywolf Wrote: [ -> ]because x = e += 1 is same as
x = e = e + 1
actually, the first one is invalid syntax and rise SynatxError,
while second one is perfectly fine
e = 10
x = e = e + 1
print x
print e
Output:
11
11
Then why would
x = e += 1 be invalid if its the same as
x = e = e + 1 ?
(May-05-2017, 06:44 AM)idontreallywolf Wrote: [ -> ]Then why would x = e += 1 be invalid if its the same as x = e = e + 1 ?
You are the one that repeatedly claims they are the same, not me.... :-)
x = e = e + 1 is called chained assignment and is valid python code.
(May-05-2017, 06:53 AM)buran Wrote: [ -> ] (May-05-2017, 06:44 AM)idontreallywolf Wrote: [ -> ]Then why would x = e += 1 be invalid if its the same as x = e = e + 1 ?
You are the one that repeatedly claims they are the same, not me.... :-)
x = e = e + 1 is called chained assignment and is valid python code.
Assignment in Python - unlike in C -
does not return value - that why in Python
if x=3 is illegal too, and Python programmers don't have to write
if 3 == x
in
x = e += 1
right operand is assignment - unlike in the example above, where right operand is
e + 1
@volcano63, I don't understand what you mean that Python programmers don't have to write
if 3 == x and once again
x = e += 1 is invalid, raising SyntaxError.
(May-05-2017, 07:22 AM)buran Wrote: [ -> ]@volcano63, I don't understand what you mean that Python programmers don't have to write if 3 == x
Many C/C++ programmers acquire the habit to write
if (3 == x) instead of
if (x == 3), because if you accidentally omit
=, the code will still compile - but the meaning will change.
if (3 = x) is illegal assignment, failing compilation.
(May-05-2017, 07:22 AM)buran Wrote: [ -> ]and once again x = e += 1 is invalid, raising SyntaxError.
I thought I was enhancing your point, not arguing it.
(May-05-2017, 01:03 PM)volcano63 Wrote: [ -> ]if (3 = x) is illegal assignment, failing compilation.
I do this all the time, because I like when the compiler tells me I'm stupid. I believe it's commonly referred to as yoda checking, because it sounds backwards. (
https://en.wikipedia.org/wiki/Yoda_conditions)