删除后的 C++ 指针然后赋值

Question

我遇到了这个问题，它创建了3块内存，如果删除*r我很困惑，**r是否还存在？我应该将 **r 移动到 *r 的位置吗？我需要另一个 "new int" 语句来提供价值吗？

int t = 5;
int **r;
r = new int *;  //declare pointer  
*r = new int;
delete *r;      // delete pointer
*r = t;         //give new value

抱歉提问有误。还在里面学习。谢谢。

Answer 1

您的代码正确 (Ideone):

#include <iostream>
using namespace std;

int main() {
    int **r = new int *; // declare pointer to int*
    cout << r << endl;   // outputs some address in memory (pointer to int*)
    cout << *r << endl;  // outputs some garbage value
//  cout << **r << endl; // it's invalid

    *r = new int;        // assign to memory pointed by r new value
    cout << *r << endl;  // outputs some address in memory (pointer to int)
    cout << **r << endl; // outputs some garbage value

    delete *r;           // delete pointer to int
    cout << *r << endl;  // outputs same address in memory, but we can't dereference it
//  cout << **r << endl; // it's invalid, because we deleted *r

    // here you can acces r, *r, but not 
    return 0;
}

删除后的 C++ 指针然后赋值

C++ Pointer after delete it then give value

c++

pointers

memory-leaks

new-operator

delete-operator