c++ - 通过实例学习指针

嗨，我遇到了这段C ++代码，并试图了解指针的操作方式。

   int main ()
{
  int firstvalue, secondvalue;
  int * mypointer;

  mypointer = &firstvalue;
  *mypointer = 10;
  mypointer = &secondvalue;
  *mypointer = 20;
  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  return 0;
}

我的问题如下：


声明int *mypointer;时，内存中到底发生了什么？
mypointer代表什么？
*mypointer代表什么？
什么时候*mypointer = 10;内存中发生了什么？

最佳答案

int * mypointer时，内存中到底发生了什么；被宣布？


从堆栈中分配了足够的内存来存储内存地址。这将是32位或64位，具体取决于您的操作系统。


mypointer代表什么？


mypointer是堆栈上包含内存地址的变量。


* mypointer代表什么？


*mypointer是mypointer指向的实际内存位置。


当* mypointer = 10时；内存中会发生什么？


值10存储在mypointer指向的存储位置中。例如，如果mypointer包含内存地址0x00004000，则值10将存储在内存中的该位置。

您的示例带有注释：

int main ()
{
  int firstvalue, secondvalue;   // declares two integer variables on the stack
  int * mypointer;               // declares a pointer-to-int variable on the stack

  mypointer = &firstvalue;       // sets mypointer to the address of firstvalue
  *mypointer = 10;               // sets the location pointed to by mypointer to 10.
                                    In this case same as firstvalue = 10; because
                                    mypointer contains the address of firstvalue
  mypointer = &secondvalue;      // sets mypointer to the address of secondvalue
  *mypointer = 20;               // sets the location pointed to by mypointer to 10.
                                    In this case same as secondvalue = 20; because
                                    mypointer contains the address of secondvalue
  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  return 0;
}

试试下面的代码，看看是否有帮助：

int main ()
{
  int firstvalue, secondvalue;
  int * mypointer;

  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  cout << "mypointer is pointing to " << mypointer << endl;

  mypointer = &firstvalue;

  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  cout << "mypointer is pointing to " << mypointer << endl;

  *mypointer = 10;

  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  cout << "mypointer is pointing to " << mypointer << endl;

  mypointer = &secondvalue;

  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  cout << "mypointer is pointing to " << mypointer << endl;

  *mypointer = 20;

  cout << "firstvalue is " << firstvalue << endl;
  cout << "secondvalue is " << secondvalue << endl;
  cout << "mypointer is pointing to " << mypointer << endl;

  return 0;
}

关于c++ - 通过实例学习指针，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/5576334/