Unusual typedef use in C++

I came 开发者_如何学Cacross a new use of the keyword typedef in C++.

What does this typedef statement mean ?

int typedef foo;

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It's the same as

typedef int foo;

i.e. it defines foo to be the type int. While the grammar allows to swap typedef and int in this case, you usually would not do this because it impairs readability.

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typedef is a decl-specifier, so it has the same syntax rules as const or static. It can be moved about like that and will mean the same thing.