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swapping two variables without a temp variable

Posted on 2001-06-08
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Last Modified: 2010-04-02
suggest code in C to swap two variables without using a temporary variable. preferably a single statement.
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Question by:falkon
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4 Comments
 
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proskig earned 150 total points
ID: 6166959
 b ^= a;
  a ^= b;
  b ^= a;

b and a will be swapped


Note also that it is C++ area
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by:harrlow
ID: 6173264
Using C..

a = a + b;
b = a - b;
a = a - b;
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by:proskig
ID: 6176416
The obvious problem with harrlow's code is that it does not work in general case due to size limit (just suppose that a and b are int's and they are close to INT_MAX)
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Expert Comment

by:EliezerGarza
ID: 7590358
but you can use:
   a=a-b
   b=a+b
   a=b-a
instead of:
   a=a+b
   b=a-b
   a=a-b
or for extra CPU usage:
   a=a*b
   b=a/b
   a=a/b
or any other of many ways. This is just an academical question, so the important thing is not if it works 100% of the cases or not, but how would you do it.

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