In Python the difference between += and =

Question

for example

A+=A=a

output:

IndentationError: unindent does not match any outer indentation level

in the same time with B+=B+b is working fine!

so whats the difference between = and += with Python

x += 1 means the same as x = x + 1. so B+=B+b means the same as B=B+B+b. The problem with the first example (A+=A=a) is the second "=" between A and a. this has nothing to do with the += — bema, Jun 07 '13 at 07:44
Running this code in `C++` gives http://ideone.com/NI1w9r Is that what you are trying to achieve? — jamylak, Jun 07 '13 at 07:46

score 0 · Accepted Answer · answered Jun 07 '13 at 07:46

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A += 1 means A = A + 1. So A += A = a would be A = A + A = a (which obviously doesnt work).

The error you seem to experience is not caused by this operator. Perhaps you mixed spaces with tabs, or you simply did not indent a certain line when it should have been.

answered Jun 07 '13 at 07:46

TerryA

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Thanks, i mixed tabs and spaces. – Nomea Jun 07 '13 at 08:18
@user2462574 Common mistake :) – TerryA Jun 07 '13 at 08:19

score 0 · Answer 2 · answered Jun 07 '13 at 07:48

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A = a It's a simple assignment, while A += a Is equivalent to

A = A + a

This occurs in most programming languages

answered Jun 07 '13 at 07:48

DevGar

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score 0 · Answer 3 · edited May 23 '17 at 12:18

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a += a would be read

a is a plus a

Therefore, A += A is

A is A plus A

A += A is short for A = A + A

The exception has nothing to do with your operator layout.

edited May 23 '17 at 12:18

Community

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answered Jun 07 '13 at 07:56

Mr_Spock

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score 0 · Answer 4 · answered Jun 07 '13 at 08:52

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what do you mean to do with A+=A=a? Make sure your purpose before you do anything.
try to do your job step by step, instead of get the whole piece at once.
a += 1 equals a = a + 1, that's the meaning and usage of +=.

answered Jun 07 '13 at 08:52

Shady Xu

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In Python the difference between += and =

4 Answers4