C++：如何编写一个接受迭代器并插入元素的函数？

Question

template<class Container>
void BlitSurface::ExtractFrames(Container & output, int frame_width, int frame_height,
                                         int frames_per_row, int frames_per_column,
                                         bool padding) const
{
    SDL_Surface ** temp_surf = SDL_Ex_ExtractFrames(_surface, frame_width, frame_height, frames_per_row, frames_per_column, padding);

    int surface_count = frames_per_row * frames_per_column;

    output.resize(surface_count);
    Container::iterator iter = output.begin();

    for(int i=0; i<surface_count; ++i, ++iter)
        iter->_surface = temp_surf[i];

    delete [] temp_surf;
}

我有这个功能将图像分割成帧并将它们存储到图像容器中。我将如何修改它以采用迭代器而不是容器，并在该点插入元素？

Answer 1

使用back_inserter:

template<typename OutputIterator>
void BlitSurface::ExtractFrames(OutputIterator it, int frame_width, int frame_height,
                                         int frames_per_row, int frames_per_column,
                                         bool padding) const
{
    /* ... other lines unchanged ...*/
    for(int i=0; i<surface_count; ++i) {
        // "BlitSurface()" sets other members to zero. Alternatively you
        // can use boost::value_initialized for that. 
        BlitSurface bs = BlitSurface();
        bs._surface = temp_surf[i];
        *it++ = bs;
    }
    delete [] temp_surf;
}

然后这样称呼它

ExtractFrames(std::back_inserter(container), ...);