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2020-03-08T05:13:41Z

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Not to be confused with "enum structs" (or "enum classes"), the struct enum is a construct for encapsulating enum values in a struct, e.g.:

<source lang="C++">
struct Foo {
enum Type {
A,
B,
C,
};
};
</source>

Usage:

<source lang="C++">
int main(int argc, char *argv[])
{
// error: 'A' was not declared in this scope
//auto x = A;

// works, 'y' has type Foo::Type
auto y = Foo::A;

// works, 'z' has type Foo::Type
Foo::Type z = Foo::A;

// works!
int u = Foo::A;

// error: invalid conversion from 'int' to 'Foo::Type'
//Foo::Type v = u;

// error: invalid conversion from 'int' to 'Foo::Type'
//Foo::Type v(u);

// works!
auto w = Foo::Type(u);

return 0;
}
</source>

=== See also ===

* https://twitter.com/kinjalkishor/status/1236108443611623424
* [[X macros]] (for an alternative way to define and introspect enums)

[[Category:Programming]]
[[Category:C++]]

Struct enum - Revision history

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