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Bit Manipulation (Overview)

“What? That title isn’t a question like you promised.” – Yep, it isn’t. I just wanted to give a short introduction of Bit Manipulation so that it might be easier for you to understand the term when I have used it in the future. An application of bit manipulation was already shown in the previous post (Find the only element in array which does not have a duplicate).

So if you don’t know it yet, all bit manipulation is about is playing around with bits to get the desired result. The most used operators for such manipulations are | (bitwise OR), & (bitwise AND), ^ (XOR), >> (right shift), << (left shift).

Hopefully, everyone will be familiar with the operation of the first 3 operators. I’ll just explain the way shift operators function.

2<<3 would give you 16. Why? In binary 2=10, shifting it right by 3 bits, we get 10000 which equals 16. Simple as that. So right shift multiplies your number by 2 raised to the number of bits you shift.

On the other hand. 16>>3 gives two. The logic is exactly opposite to the one for right shit. Thus, left shift ends up dividing a number by 2 raised to the number of bits you shift. Easy-peasy!

You will be amazed to see the applications of such bit-manipulations to problems. Some problems are rendered so easy with the use of these operators that it would almost make you laugh. Other problems (like finding ‘a*7’ for a given ‘a’ without using *,/,+) necessarily require the use of bit manipulations. We will soon discuss more applications where bit manipulations make your life easier. 🙂

PS: The solution for the question in bold is –

b=a<<3; print b-a; //in essence, multiplying number by 8 and then subtracting it once from the result of the shifting 😉

More cool stuff follows soon.

 

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