Can anyone explain why '>>2' shift means 'divided by 4' in C codes?

Question

I know and understand the result.

For example:

 7 (decimal) = 00000111 (binary) 


and 7 >> 2 = 00000001 (binary) 

        

Answer 1

An easy way to see why it works, is to look at the familiar decimal ten-based number system, 050 is fifty, shift it to the right, it becomes 005, five, equivalent to dividing it by 10. The same thing with shifting left, 050 becomes 500, five hundred, equivalent to multiplying it by 10.

All the other numeral systems work the same way.

Answer 2

You can call it an idea of a genius mind or just the need of the computer language.

To my belief, a Computer as a device never divides or multiplies numbers, rather it only has a logic of adding or simply shifting the bits from here to there. You can make an algorithm work by telling your computer to multiply, subtract them up, but when the logic reaches for actual processing, your results will be either an outcome of shifting of bits or just adding of bits.

You can simply think that for getting the result of a number being divided by 4, the computer actually right shifts the bits to two places, and gives the result:

7 in 8-bit binary = 00000111
Shift Right 2 places = 00000001 // (Which is for sure equal to Decimal 1)

Further examples:
//-- We can divide 9 by four by Right Shifting 2 places
9 in 8-bit binary = 00001001
Shift right 2 places: 00000010 // (Which is equal to 9/4 or Decimal 2)

A person with deep knowledge of assembly language programming can explain it with more examples. If you want to know the actual sense behind all this, I guess you need to study bit level arithmetic and assembly language of computer.

Answer 3

they do that because shifting is more efficient than actual division. you're just moving all the digits to the right or left, logically multiplying/dividing by 2 per shift

If you're wondering why 7/4 = 1, that's because the rest of the result, (3/4) is truncated off so that it's an interger.

Answer 4

Its inherent in the binary number system used in computer.

a similar logic is --- left shifting 'n' times means multiplying by 2^n.