<< operator in C++?

Question

I am new to C++, what's the exact meaning for the << in statement below, Thanks.

if (Val & (0x0001 << 0))
{}
else
{}

Answer 1

It is a shift-left operation. If you have:

a << b

where a and b are integral types (char, short, long, etc.), then the bits in a are shifted left b places with zeroes filling in on the right. In other words, a is multiplied by 2^b.

Example:

12 << 3

12 (decimal) = 00001100 (binary)

shift left 3 places:

00001100 becomes 01100000 

which is 96 (which is 12 * 8 or 12 * 2^3)

Answer 2

It means shift 0x0001 number 0 bits to the left. In that specific case, it does nothing.

For example, if it was (0x0001 << 4), 0x0001 would become 0x0010. Each position shifted left is like multiplying the number by 2.

Answer 3

That is a bit shift operator.

But when integers aren't involved, beware of an underlying overloaded operator.