C++ 空指针和野指针

淡淡的烟草味﹌ 2023-02-20 02:13 48阅读 0赞

//1，指针变量指向内存中编号为0的空间为空指针  
    //2，空指针指向的内存空间是不可以访问的

#include<iostream>
    using namespace std;
    int main() {
    
    
    
    	int a = 10;
    	int * p = &a;
    	cout << p << endl;
    	cout << &a << endl;
    
    	cout << "指针占" << sizeof(int *) <<"字节" << endl;
    	cout << "指针占" << sizeof(p) << "字节" << endl;
    
    	//1，指针变量指向内存中编号为0的空间为空指针
    	//2，空指针指向的内存空间是不可以访问的
    
    	int * q = NULL;
    	//0-255内存编号为系统占用，不允许用户访问
    	cout << *q << endl;
    
    	system("pause");
     }

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野指针:指针变量指向非法的内存空间

#include<iostream>
    using namespace std;
    
    
    int yezhizhen() {
    	//指针变量p指向内存地址编号为0x1100的空间
    	int * p = (int *)0x1100;
    	//访问野指针报错
    	cout << *p << endl;
    	system("pause");
    	return 0;
    }

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