search

Home  >  Q&A  >  body text

c++ - “一个指针指向某对象,同时另一个指针指向另外对象的下一地址,两个指针可能相等”是怎么回事?

《C++ Primer》第五版,中文版。p50。
需要注意的是,一个指针指向某对象,同时另一个指针指向另外对象的下一地址,此时也有可能出现这两个指针值相同的情况,即指针相等。

之前在 CSDN 问答上问的:http://ask.csdn.net/questions/256146
“另外对象的下一地址”指的是不是尾后迭代器?
有人提到是相邻的导致相等。是否是下面的代码表达的意思:

#include <iostream>
#include <iterator>

using namespace std;

int a[] = { 1,2 };
int i = 4;

int main()
{

    int *p = end(a);
    if (p == &i) cout << "equ" << endl;

    return 0;
}
高洛峰高洛峰2813 days ago923

reply all(3)I'll reply

  • 巴扎黑

    巴扎黑2017-04-17 13:50:47

    Regarding your question, I don’t know if I understand the meaning of the description correctly. Look at the picture below

    This is very simple, it is possible to be equal. When object C and object B are one object, they are equal.
    I’ll lend you the code

    #include <iostream>
    #include <iterator>
    
    using namespace std;
    
    int a[] = { 1,2 };
    
    int main()
    {
        int* p1 = &a[1];        //指针p1指向对象a[1]
        int* p2 = &a[0] + 1;    //指针p2指向对象a[0]的下一个
        if(p1 == p2){
            cout<<"p1("<<p1 <<") = p2("<<p2<<")\n";
        }
        return 0;
    }

    reply
    0
  • PHPz

    PHPz2017-04-17 13:50:47

    a-b-c-d-....
    p1=b;
    p2=a->next;

    p1==p2

    reply
    0
  • 大家讲道理

    大家讲道理2017-04-17 13:50:47

    因为内存是连续的, after the file pointer p completes traversing the array, it actually points to a memory address behind the array. The next memory address happens to be the address of i. So they are exactly equal. I think the following two pictures will solve your doubts:

    Calculate the memory address yourself, an integer is 4 bytes. Did it happen to correspond?

    reply
    0
  • Cancelreply