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C++ is also more strict in conversions to enums: ints cannot be implicitly converted to enums as in C. Also, enumeration constants (enum enumerators) are always of type int in C, whereas they are distinct types in C++ and may have a size different from that of int. [needs update] In C++ a const variable must be initialized; in C this is not ...
The Java standard library provides utility classes to use with enumerations. The EnumSet class implements a Set of enum values; it is implemented as a bit array, which makes it very compact and as efficient as explicit bit manipulation, but safer. The EnumMap class implements a Map of enum values to object. It is implemented as an array, with ...
enum Enum1; // Invalid in C++03 and C++11; the underlying type cannot be determined. enum Enum2: unsigned int; // Valid in C++11, the underlying type is specified explicitly. enum class Enum3; // Valid in C++11, the underlying type is int. enum class Enum4: unsigned int; // Valid in C++11. enum Enum2: unsigned short; // Invalid in C++11 ...
C++ has enumeration types that are directly inherited from C's and work mostly like these, except that an enumeration is a real type in C++, giving added compile-time checking. Also (as with structs), the C++ enum keyword is combined with a typedef, so that instead of naming the type enum name, simply name it name.
The enum types in the Rust, Haxe, and Swift languages also work as tagged unions. The variant library from the Boost C++ Libraries demonstrated it was possible to implement a safe tagged union as a library in C++, visitable using function objects.
This code looks like it should compile, but it is incorrect because the compiler does not know if T::bar is a type or a value. The reason it doesn't know is that T::bar is a "template-parameter dependent name", or "dependent name" for short, which then could represent anything named "bar" inside a type passed to foo(), which could include typedefs, enums, variables, etc.
converting a pointer of a base class to a pointer of a non-virtual derived class (downcasting); converting numeric data types such as enums to ints or floats . Although static_cast conversions are checked at compile time to prevent obvious incompatibilities, no run-time type checking is performed that would prevent a cast between incompatible ...
Another way is to make another class that extends java.lang.Enum<E>) and may therefore define constructors, fields, and methods as any other class. As of C++11, C++ supports strongly-typed enumerations which provide more type-safety and explicit specification of the storage type.