It's worth noting, on top of these other answers, that C++20 solves one of the problems that enum class has: verbosity. Imagining a hypothetical enum class, Color.
void foo(Color c)
switch (c) {
case Color::Red: ...;
case Color::Green: ...;
case Color::Blue: ...;
// etc
}
}
This is verbose compared to the plain enum variation, where the names are in the global scope and therefore don't need to be prefixed with Color::.
However, in C++20 we can use using enum to introduce all of the names in an enum to the current scope, solving the problem.
void foo(Color c)
using enum Color;
switch (c) {
case Red: ...;
case Green: ...;
case Blue: ...;
// etc
}
}
So now, there is no reason not to use enum class.