Hello CF!
Let me ask you, what is 3 & 6 (where & is the bitwise AND operator)?
You'll answer 2, right? Well, I wrote this piece of code (don't remember why)
if (3 & 6 == 2) cout << "Equal";
else cout << "Not Equal";
...and the output is
What in this universe happened??? Though this might seem obvious to some, it potentially could cost you a whole problem... Let me briefly explain the "why" so you don't make the same error I made.
The reason is Operator Precedence
Counter-intuitively, operators like &, ^, | should all have a higher precedence than == in C++, turns out this is not the case!
Have a look here
Thus the above code actually is if (3 & (6 == 2))
which is if (0)
So, the takeaway is to always wrap bitwise operations in parenthesis to avoid such mistakes.
Here's the correct code, which gives the desired output "Equal"
if ((3 & 6) == 2) cout << "Equal";
else cout << "Not Equal";
Hope this helps!
Modern compilers will warn you about that. I personally compile all my code with
-Wall -Wextra -Wshadow
. I also recommend adding-Werror
so it's impossible to ignore warnings.g++'s output:
Wow, thanks for adding! I'll compile with them from now on too
I have had this bug in my code before and tbh debugging is a nightmare.