Question

int main()
{
    int i=3;
    (i << 1);
    cout << i; //Prints 3
}

I expected to get 6 because of shifting left one bit. Why does it not work?

Answer 1

Because the bit shift operators return a value.

You want this:

#include <iostream>

int main()
{
     int i = 3;
     i = i << 1;
     std::cout << i;
}

The shift operators don’t shift “in place”. You might be thinking of the other version. If they did, like a lot of other C++ binary operators, then we’d have very bad things happen.

i <<= 1; 

int a = 3;
int b = 2;
a + b;    // value thrown away
a << b;   // same as above