问个问题，Mat的channel明明返回是Mat类型，为什么可以用float*来接？

[mozheng]

NCNN_FORCEINLINE Mat Mat::channel(int _c)
{
    Mat m(w, h, d, (unsigned char*)data + cstep * _c * elemsize, elemsize, elempack, allocator);
    m.dims = dims - 1;
    if (dims == 4)
        m.cstep = (size_t)w * h;
    return m;
}

NCNN_FORCEINLINE const Mat Mat::channel(int _c) const
{
    Mat m(w, h, d, (unsigned char*)data + cstep * _c * elemsize, elemsize, elempack, allocator);
    m.dims = dims - 1;
    if (dims == 4)
        m.cstep = (size_t)w * h;
    return m;
}

还有一个问题：ncnn::Mat怎么从一个float* 构建。谢谢大家

[nihui]

Mat 有个方法返回任意类型的指针

    // access raw data
    template<typename T>
    operator T*();
    template<typename T>
    operator const T*() const;