This is hardly newsworthy. If the extensions were called ‘Jabberwocky C Extennsions’ no one would have cared. The extension allows for tagged unnamed structs inside of a struct, e.g.:
Tag is what goes after the struct keyword to allow referring to the struct type. Structs don’t have to have a tag. Name is what field are called. Adapting Obin’s example:
This is hardly newsworthy. If the extensions were called ‘Jabberwocky C Extennsions’ no one would have cared. The extension allows for tagged unnamed structs inside of a struct, e.g.:
struct inner { /* ... */ }; struct outer { int value; struct inner; };Untagged?
You mean ‘unnamed’ is what’s confusing you?
Normally you can do anonymous struct/union members or struct struct/union members that are tagged structs but not anonymous.
I.e. in standard C you’d have to do either:
struct foo { int baz; }; struct bar { struct foo foo; }; ... struct bar data; data.foo.baz = 0;or:
struct bar { struct { int baz; } foo; }; ... struct bar data; data.baz = 0;but to do the following, you’d need the extension:
struct foo { int baz; }; struct bar { struct foo; }; ... struct bar data; data.baz = 0;Minor correction: Unnamed structs and unions (so your second example) are not part of C. They are GNU extensions.Unless I’m misunderstanding something, I’m pretty sure they’ve been standardized in C11. Also mentioned here.
You appear to be correct.
Tag is what goes after the
structkeyword to allow referring to the struct type. Structs don’t have to have a tag. Name is what field are called. Adapting Obin’s example:struct foo { int baz; }; struct bar { struct foo qux; }; struct bar data; data.qux.baz = 0;fooandbarare tags forstruct fooandstruct bartypes respectively;bazandquxare field names; anddatais a variable name.