How to determine how many bytes an integer needs?

Question

I\'m looking for the most efficient way to calculate the minimum number of bytes needed to store an integer without losing precision.

e.g.

int: 10 = 1 byte
         


        

Answer 1

For each of eight times, shift the int eight bits to the right and see if there are still 1-bits left. The number of times you shift before you stop is the number of bytes you need.

More succinctly, the minimum number of bytes you need is ceil(min_bits/8), where min_bits is the index (i+1) of the highest set bit.