Bit operations: Test a bit
Problem: given int i, is bit n set (equal to 1)?
    bn b0
i 0000 0000 0000 0000
0000
0000 0000 0010
bit n
How can we test if this bit is 1?
We can use & operator with a "mask" variable:
mask 0000 0000 0000 0000
0010
0000 0000 0000
if (i & mask)
printf ("yes");
else
printf ("no");
What is the problem with this?