编程基础之 Stack和Heap的区别-CFANZ编程社区

Stack和Heap在哪儿

都在RAM，即都在内存中存放

Stack

在一个函数被调用时候，在stack会保留一块以用来保存local variables。函数返回时，这块stack成为Unuse的状态，提供给下一个函数的使用。

function func(){
  int i = 1; // Allocated on stack
} // De-allocated from stack

function func1(){
  int j = 2; // Allocated on stack
}// De-allocated from stack


void main(){
  func();
  func1();
}

Heap

Heap的分配和释放比较自由，可以随时分配，并且随时释放。

new 和 malloc创建的东西将会存放到Heap中，属于dynamic allocation

function func(){
  int i = 1; // Allocated on stack
  Char* buffer = new Char[20]; // Allocated on heap
  doSomething;
  deallocated buffer; //deallocated from heap
  doSomethingElse;
}//deallocated from stack

Thread中的Stack和Heap的关系

每个thread都有自己的Stack，同一process下的Threads之间共享一个Heap。

例子

Stack和Heap的分配

int i = 1; // Allocated on stack
Char* string = "Vigor"; //Allocated on stack
Char* buffer = new Char[20]; // Allocated on heap


int foo()
{
  char * pBuffer;
  //<--nothing allocated yet (excluding the pointer itself, which is allocated here on the stack).
  bool b = true;
  // Allocated on the stack.
  if(b)
  {
    //Create 500 bytes on the stack
    char buffer[500];

    //Create 500 bytes on the heap
    pBuffer = new char[500];

   }
   //<-- buffer is deallocated here, pBuffer is not
} //<--- oops there's a memory leak, I should have called delete[] pBuffer;