Use of <<++ and >>++ operators in C++

Question

I have encountered <<++ and >>++ operators many time in`C++, but I don't understand what they are. What is the specific meaning and use of these operators, and how are they different from right shift and left shift operator?

I'm pretty sure that's just `>>` and `++` operators squished together. There's a famous question where someone wrote a dumb loop condition that resembles that. — Carcigenicate, Jun 02 '18 at 17:01
Very related: https://stackoverflow.com/questions/1642028/what-is-the-operator-in-C even though it's different operators, and C. — Carcigenicate, Jun 02 '18 at 17:02
Also, your title doesn't match the body. The ones in the body make sense. I don't think the ones in the title could be possible though. Sticky shift key? — Carcigenicate, Jun 02 '18 at 17:04
Can you please provide a sample code snippet involving `<>++`? — Ṃųỻịgǻňạcểơửṩ, Jun 02 '18 at 17:07

score 1 · Accepted Answer · answered Jun 02 '18 at 17:12

C++ compilers ignore whitespace unless in certain situations such as string literals.

<<++ and >>++ is really just a bit-shift operatior << or >>, followed by an increment operator ++.

Consider this code:

a <<++ b is equivalent to
a<<++b because the spaces are ignored in this context, and then equivalent to
a << ++b (a left shifted by a pre-incremented b)
a << (++b) due to operator precedence. Bit shift operators have lower precedence than incrementation.

That's a weird way to describe it. `a < – Justin Jun 03 '18 at 05:45 — Justin, Jun 03 '18 at 05:45

score 0 · Answer 2 · answered Jun 02 '18 at 17:06

0

There are two separate operators in both cases: left shift (<<), right shift (>>) and increment operator (++).

You can rewrite the following:

a >>++ b

as:

a >> (++b)

answered Jun 02 '18 at 17:06

joe_chip

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Use of <<++ and >>++ operators in C++

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