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

It is actually defined that way in the C standard.

From section 6.5.7:

The result of E1 >> E2 is E1 right-shifted E2 bit positions. [...] the value of the result is the integral part of the quotient of E1 / 2^E2

On most architectures, x >> 2 is only equal to x / 4 for non-negative numbers. For negative numbers, it usually rounds the opposite direction.

Compilers have always been able to optimize x / 4 into x >> 2. This technique is called "strength reduction", and even the oldest compilers can do this. So there is no benefit to writing x / 4 as x >> 2.