初始化动态数组元素为零

对于一个固定的阵列，

  // will initialize the missing elements to 0 as well
   A[max_row][max_col] = {0,} 

我们能在动态数组（多维的，尤其是）？做到这一点。

Can we achieve this in dynamic arrays (multidimensional, in particular)?

侧的问题：如果我们不能，我们不得不使用嵌套循环，那么如何上面相比嵌套循环初始化的伎俩初始化时间？

Side question: if we can't, and we are forced to use nested loop, then how does the initialization time of the trick above compared to nested loop initialization?

我不想矢量，否则这个问题是没有意义的。谢谢你的提醒:)

I don't want to vector, otherwise this question is meaningless. Thanks for the advise :)