Bitshift and equals together

Question

What does >>= do in this example?

byte fsr = 2;
fsr >>= 2;

StackOverflow has a better search engine than Google, so you can search for the token directly (in quotes): http://stackoverflow.com/search?q=%22%3E%3E=%22 — 1'', May 23 '13 at 01:50
You may also use your common sense (if any) to search for a [slightly broader category](http://en.wikipedia.org/wiki/Operators_in_C_and_C%2B%2B). — , May 23 '13 at 02:10
Does this answer your question? [What does <<= operator mean in Java?](https://stackoverflow.com/questions/12071826/what-does-operator-mean-in-java) — Zoe, Sep 24 '20 at 14:36

score 11 · Answer 1 · answered May 23 '13 at 01:45

11

It does this:

fsr = fsr >> 2;

answered May 23 '13 at 01:45

gzm0

2

(However it will evaluate `fsr` only once, in cases where `fsr` is an expression that has side-effects on evaluation. In other cases it is 100% equivalent) – Patashu May 23 '13 at 01:47
@Patashu, you mean like `*getPtr() >>= 2;` where `getPtr` has a side-effect? – gzm0 May 23 '13 at 01:49
@gxzm0 Yes, think about what the equivalent code without `>>=` is. – Patashu May 23 '13 at 01:50
@Patashu `byte* ptr = getPtr(); *ptr = *ptr >> 2;` – gzm0 May 23 '13 at 01:51
1

@gxzm0 I was thinking more like `*getPtr() = *getPtr() >> 2` – Patashu May 23 '13 at 01:52
This is called an *in-place shift operator*. – paddy May 23 '13 at 01:52

score 2 · Answer 2 · answered May 23 '13 at 02:07

2

fsr >>= 2;

is

fsr = fsr >> 2;

In Bitwise Context, two bit places to the right is being shifted.

In Arithmetic context, the number in fsr is being divided by 2^2(4);

answered May 23 '13 at 02:07

Barath Ravikumar

2 Answers2