c++二级指针如何手动释放？double** PP = new double* [NSEG + 1];

Question

double** PP = new double* [NSEG + 1];//如何手动释放？我看网上说依次释放内存空间，我下面这样释放对吗？

if (PP != NULL)
{
delete[] PP;
PP = NULL;
}
if (* PP != NULL)
{
delete[] * PP;
* PP = NULL;
}

Answer 1

不需要双层释放，这样就行。
除非你pp的每个元素如pp[0], pp[1]也用了new，那就要双层释放，那也是先释放pp[0], pp[1]， 再释放PP
if (PP != NULL)
{
delete[] PP;
PP = NULL;
}