在C ++中将2D数组传递给使用括号表示法的问题

Question

I have a struct that holds some information about an animation, I want to be able to initialize the struct with a 2D array, without creating and initializing the array first.

The constructor of my Animation struct is as follows:

Animation( int frames[][2], int count );

I want to achieve something like this:

Animation* m_PlayerAnimation = new Animation( { { 3, 9 }, { 11, 9 }, { 19, 9 } }, 3 );

I know it's possible as follows, however I'm looking for a 1-line solution:

int arr[][2] = { { 3, 9 }, { 11, 9 }, { 19, 9 } };
Animation* m_PlayerAnimation = new Animation( arr, 3 );

Thanks in advance!

Answer 1

The issue is where you have the argument int frames[][2] , frames is a pointer. So you can't create something in-place there, since it won't be a pointer. This is a holdover from C.

If you want to be able to in-place create an arbitrary array, you'll have to change your constructor to:

template <size_t N>
Animation(const int (&frames)[N][2]) { .. }

which lets you write:

Animation a({{0,1}});

At this point the count argument becomes redundant, as it's replaced by the template parameter N .

Alternatively, you could just use vector :

Animation(std::vector<std::array<int, 2>> const& v) { .. }

which can be used the same way:

Animation a({{0, 1}});