[trivial][doc] Mention ++i as preferred over i++ in dev notes #8602

pull fanquake wants to merge 1 commits into bitcoin:master from fanquake:trvial-dev-notes changing 1 files +4 −3

fanquake commented at 11:41 AM on August 26, 2016: member

Comment from @sipa here.
[trivial][doc] Mention ++i as preferred to i++ in dev notes ab53207b9c
sipa commented at 11:47 AM on August 26, 2016: member

utACK
laanwj commented at 12:33 PM on August 26, 2016: member

ACK https://github.com/bitcoin/bitcoin/pull/8602/commits/ab53207b9cdb6422cbb515ca6acf1bf945651895
laanwj merged this on Aug 26, 2016
laanwj closed this on Aug 26, 2016
laanwj referenced this in commit bb566761fb on Aug 26, 2016
in doc/developer-notes.md:None in ab53207b9c
```
  13 | @@ -14,6 +14,7 @@ gradually.
  14 |    - No indentation for public/protected/private or for namespaces.
  15 |    - No extra spaces inside parenthesis; don't do ( this )
  16 |    - No space after function names; one space after if, for and while.
  17 | +  - `++i` is preferred over `i++`.
```
MarcoFalke commented at 6:00 PM on August 26, 2016:

Nit: Sorry to nitpick this after merge, but I'd rather put it in the section General C++ (line 253) and also mention that i++ is fine for integers.

You can copy the rationale from the cpp guide

When the return value is ignored, the "pre" form (++i) is never less efficient than the "post" form (i++), and is often more efficient. This is because post-increment (or decrement) requires a copy of i to be made, which is the value of the expression. If i is an iterator or other non-scalar type, copying i could be expensive. Since the two types of increment behave the same when the value is ignored, why not just always pre-increment?

sipa commented at 6:02 PM on August 26, 2016:

I agree here. This is not just a style issue, as it may affect generated code.
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#8579 Performance: Prefer prefix operator for non-primitive types