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Comment by brandmeyer | Hacker News Reader

This might be my biggest gripe with C's syntax.

typename identifier[];

means three different things, depending on where it appears: As a function argument, it is a pointer that will be accessed like an array. As a variable with automatic storage duration, it is an array whose size will be determined by the right-hand-side of an assignment from a braced initializer list. In the middle of a struct definition, it's illegal. And at the end of a struct definition, it is a flexible array member.

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My favorite is similar thing, but in C++ and much more confusing:

  class Bar {};
  
  class Foo {
  public:
  	Foo(const Bar &c) { }
  	void method() { }
  };
  
  int main() {
  	Foo foo(Bar());
  	foo.method();
  	return 0;
  }

"foo.method();" doesn't compile because:

  error: request for member ‘method’ in ‘foo’, which is of non-class type ‘Foo(Bar (*)())’

That's right: "foo" is a declared function that returns instance of Foo and takes one argument - a function that returns instance of Bar :) But when you add additional parentheses in a line above:

  Foo foo((Bar()));

then "foo" is an instance of Foo created by passing a new instance of Bar to its constructor, which is more like what you'd expect by reading the code, and the code compiles. Fun!

Yes, the most vexing parse.

https://en.wikipedia.org/wiki/Most_vexing_parse

C++11 initialization syntax solves this

https://en.wikipedia.org/wiki/Most_vexing_parse#Uniform_init...

I believe this situation is usually referred to as the "Most vexing parse".

As an extern'd variable it's an array of unknown length

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