How does a 'const struct' differ from a 'struct'?

Question

What does const struct mean? Is it different from struct?

Answer 1

It means the struct is constant i.e. you can't edit it's fields after it's been initialized.

const struct {
    int x;
    int y;
} foo = {10, 20};
foo.x = 5; //Error

EDIT: GrahamS correctly points out that the constness is a property of the variable, in this case foo, and not the struct definition:

struct Foo {
    int x;
    int y;
};
const struct Foo foo = {10, 20};
foo.x = 5; //Error
struct Foo baz = {10, 20};
baz.x = 5; //Ok