swap values - the Python way

It's a very well known problem given to the beginners, 'swap values of two variables'. In our first introductory programming course (structured programming in C) we solved it in different ways. Most of us used another temporary variable. Some of us did some math tricks. I remember that one of my friend wrote the following code (in C):
int a, b;
scanf("%d %d", &a, &b);
printf("%d %d\n", b, a);

And it made us laugh :-D

Here is the pythonic way of doing this. Try the following code:
a = 2
b = 3
print a, b
a, b = b, a
print a, b

:-)

Comments

Unknown said…
Thanks a lot! Nicely done :)
March 23, 2010 at 7:07 AM
madchuckle said…
Yes, this is one of the coolest features of Python. In fact, it uses sequence-packing-unpacking in the stack itself and is more faster than the math trick:

y = x^y
x = x^y
y = x^y

trick. The assembly code for proof can be found here. Great blog btw, as a new convert to Python, I'll follow your posts from now on.

MadChuckle Blog
May 1, 2010 at 9:22 PM
Japan Shah said…
how can I swap two values from list?
June 25, 2010 at 4:01 PM
Chris said…
@Japan Shah You can swap two values from a list with:

l[i],l[j]=j[j],l[i]
October 6, 2010 at 3:54 AM
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