在 C++ 中正确使用堆栈和堆?

No, the difference between stack and heap isn't performance. It's lifespan: any local variable inside a function (anything you do not malloc() or new) lives on the stack. It goes away when you return from the function. If you want something to live longer than the function that declared it, you must allocate it on the heap.

class Thingy;

Thingy* foo( ) 
{
  int a; // this int lives on the stack
  Thingy B; // this thingy lives on the stack and will be deleted when we return from foo
  Thingy *pointerToB = &B; // this points to an address on the stack
  Thingy *pointerToC = new Thingy(); // this makes a Thingy on the heap.
                                     // pointerToC contains its address.

  // this is safe: C lives on the heap and outlives foo().
  // Whoever you pass this to must remember to delete it!
  return pointerToC;

  // this is NOT SAFE: B lives on the stack and will be deleted when foo() returns. 
  // whoever uses this returned pointer will probably cause a crash!
  return pointerToB;
}

为了更清楚地了解堆栈是什么，从另一端开始――而不是尝试从高级语言的角度理解堆栈的作用，查找调用堆栈"和调用约定"看看当你调用一个函数时机器真正做了什么.计算机内存只是一系列地址；堆"和栈"是编译器的发明.