C++ 指针 new delete 赋值各种情况总结

#include<iostream>
using namespace std;

int main()
{
int* a = new int(100);
std::cout << *a << " " << a << std::endl;

//情况1 普通变量b
/*
* 结果
* 100 0x440f010
* 100 0x7fff6ff320d4
*/
#if 0
int b = *a;
std::cout << b << " " << &b << std::endl;
#endif

//情况2 普通变量b delete a
/*
* 结果
* 100 0x5fc2010
* 100 0x7fff3b6d7384
*/
#if 0
int b = *a;
delete a;
std::cout << b << " " << &b << std::endl;
#endif

//情况3 指针变量b
/*
* 结果
* 100 0x12094010
* 100 0x12094010
*/
#if 0
int* b = a;
std::cout << *b << " " << b << std::endl;
#endif

//情况4 指针变量b delete a
/*
* 结果
* 100 0xdc28010
* 0 0xdc28010
*/
#if 0
int* b = a;
delete a;
std::cout << *b << " " << b << std::endl;
#endif

//情况5 new指针变量b
/*
* 结果
* 100 0x10066010
* 0 0x10066030
* 100 0x10066010
*/
#if 0
int* b = new int();
std::cout << *b << " " << b << std::endl;
b = a;
std::cout << *b << " " << b << std::endl;
#endif

//情况6 new指针变量b delete a
/*
* 结果
* 100 0x2c18010
* b Value::0 b ptr::  0x2c18030
* b Value::0 b ptr::  0x2c18010
* a Value::0 a ptr::  0x2c18010
*/
#if 0
int* b = new int();
std::cout << "b Value::" <<  *b << " b ptr::  " << b << std::endl;
b = a;
delete a;
std::cout << "b Value::" <<  *b << " b ptr::  " << b << std::endl;
std::cout << "a Value::" <<  *a << " a ptr::  " << a << std::endl;
#endif

//情况7 new指针变量b delete b
/*
* 结果
* 100 0x81d8010
* b Value::0 b ptr::  0x81d8030
* b Value::0 b ptr::  0x81d8010
* a Value::0 a ptr::  0x81d8010
*/
#if 0
int* b = new int();
std::cout << "b Value::" <<  *b << " b ptr::  " << b << std::endl;
b = a;
delete b;
std::cout << "b Value::" <<  *b << " b ptr::  " << b << std::endl;
std::cout << "a Value::" <<  *a << " a ptr::  " << a << std::endl;
#endif
return 0;
}