Conditional check for “i == (2^8)” fails when i is 512?

Question

Here is a small Program to print powers of 2 till 8. But it is not quitting after 8. Please explain the reason.

#include 
#include 

        

Answer 1

The problem is that ^ is the Bitwise XOR operator, not raise to power. Let's explain 2^8 in bitwise format:

2 = 0010
8 = 1000
======== xor
10= 1010

so the result, applying xor bit by bit, is 10, that never happens so your loop never exits. You can make your unit test working if you use pow(2,8) and round to integer instead.

Another information, it is probably not the case in this example, but it is better to avoid the strict equality when working with floating point values, compare with an epsilon is better.

For your edit: Ensure the precedence with this:

if((2^8) == (1<<8))

this will return false, as expected.