c++中指针,指针的引用,指针的指针的区别

c++中指针,指针的引用,指针的指针的区别 - C++ Programmer's Cookbook - C++博客

c++中指针,指针的引用,指针的指针的区别

看例子和结果:



#include"stdafx.h"

#include<iostream>

usingnamespacestd;

voidFreePtr1(intptr1)

{

delete ptr1;

ptr1=NULL;

}



voidFreePtr2(int&ptr2)

{

delete ptr2;

ptr2=NULL;

}

voidFreePtr3(intptr3)

{

deleteptr3;

ptr3=NULL;

}



voidmain()

{

cout<<"---------------------------------------"<<endl;

intp1=newint;

p1=1;

cout<<"p1="<<p1<<endl;

FreePtr1(p1);

cout<<"after call freePtr1"<<endl;

if(p1!=NULL)

{

cout<<"p1 is not null"<<endl;

cout<<"p1="<<(p1)<<endl;

}

cout<<"---------------------------------------"<<endl;

intp2=newint;

p2=2;

cout<<"p2="<<p2<<endl;

FreePtr2(p2);

cout<<"after call freePtr2"<<endl;

if(p2!=NULL)

{

cout<<"p2="<<p2<<endl;

}

else

{

cout<<"the p2 is null"<<endl;

}

cout<<"---------------------------------------"<<endl;

intp3 ;

p3=newint(3);

cout<<"p3="<<p3<<endl;

FreePtr3(&p3);

cout<<"after call freePtr3"<<endl;

if(p3!=NULL)

{

cout<<"p3="<<p3<<endl;

}

else

{

cout<<"the p3 is null"<<endl;

}

cout<<"---------------------------------------"<<endl;

system("pause");



}

结果:







comments:



对p1指针:

cout<<"---------------------------------------"<<endl;

int p1 = new int;

p1 = 1;

cout<<"p1="<<p1<<endl;



// FreePtr1(p1);

void FreePtr1(int ptr1)

{



delete ptr1;



ptr1 = NULL;



}



cout<<"after call freePtr1"<<endl;

if(p1 != NULL)

{

cout<<"p1 is not null"<<endl;

cout<<"p1="<<(p1)<<endl;

}

cout<<"---------------------------------------"<<endl;



而p2为:

调用前:



调用后:







注意:函数的参数进行值拷贝,即使传的是指针,也的对指针(即指针里存的地址)的拷贝,可不是指针里地址所指的值的拷贝啊!原文链接: https://www.cnblogs.com/lexus/archive/2013/01/22/2870686.html

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