NOT(~) vs NEGATION(!)

When i gets to -1, the value of ~i is ~-1, or 0, so the while loop stops executing. The ! operator works because it does something completely different; it results in 1 for 0 values and 0 for all other values. ~ is a bitwise negation.

A little more in detail:

• ~ takes each bit in a number and toggles it. So, for example, 10010₂ would become 01101₂
• -1 is all ones in binary when a two’s complement signed integer.
• ~0b…11111111 is 0.

However:

• !0 is 1, !anythingElse is 0
• -1 is not 0
• !-1 is still 0

And if you actually want to loop including i == -1, just use while (i) instead of while (~i).