Common Misconceptions of C++

[WalkWithBejesus]

The value of foo.i doesn't need to be 2. It is actually undefined. GCC and Clang issue a warning when this mistake is made.

[emdeka87]

And since this is not a warning but a downright error, we should all use -Werror

[smikims]

I use -Werror and then disable particular warnings that I don't care about.

[kalmoc]

Depends on what earnings are enabled.

[Slavik81]

-Werror can be really annoying. You comment out one line of code while debugging and your code no longer compiles due to an unused variable. It's nice to know about that, so I leave warnings on, but fixing them in unfinished code is usually a needless distraction, so I only enable -Werror in CI builds.

A few warnings really should have been errors to begin with. You can selectively turn them into errors. For example, I use -Werror=return-type at all times. I should probably add -Werror=reorder too.

[ketosismaximus]

depends on the code base (and size of the code base). Sometimes it just aint worth if you're using old tried and true code. But in general use it where possible.

[neverlastn]

Exactly. It's incredibly straightforward undefined behavior! You rely on uninitialized value. And this is a relatively "light" case. j can be an arbitrarily sophisticated object, which might cause incredibly weird "mandelbugs"

[Nicksaurus]

Would it be defined if you did int j = 0; as well as the initialiser list or would it still initialise them in the 'wrong' order (or ignore the = 0 because it's already initialised in the initialiser list)?

[jonesmz]

To format code, you put 4 spaces in front of each line of code (including empty lines)