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How to add two numbers without using ++ or + or another arithmetic operator

Asked 2009-07-19T13:45:57.170
54

How do I add two numbers without using ++ or + or any other arithmetic operator?

It was a question asked a long time ago in some campus interview. Anyway, today someone asked a question regarding some bit-manipulations, and in answers a beautiful quide Stanford bit twiddling was referred. I spend some time studying it and thought that there actually might be an answer to the question. I don't know, I could not find one. Does an answer exist?

c++ c algorithm bit-manipulation
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For unsigned numbers, use the same addition algorithm as you learned in first class, but for base 2 instead of base 10. Example for 3+2 (base 10), i.e 11+10 in base 2:

   1         ‹--- carry bit
   0 1 1     ‹--- first operand (3)
 + 0 1 0     ‹--- second operand (2)
 -------
   1 0 1     ‹--- total sum (calculated in three steps)
answered 2009-07-19T15:16:59.713

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