C/C++中的const int*和int * const

代码：

 1 #include <iostream> 
 2 
 3 using namespace std; 
 4 
 5 int main(){
 6     const int *p;
 7     int a = 2;
 8     p = &a;
 9     a = 5;
10     
11     cout<<p<<" "<<*p<<endl;
12 
13     int b = 10;
14     p = &b;
15 
16     cout<<p<<" "<<*p<<endl;
17 
18     //*p = 1; 错误，不允许修改，*p是常量
19     //cout<<*p<<endl;
20     
21     int * const p1 = &a;//此处必须初始化，否则编译错误
22     cout<<p1<<" "<<*p1<<endl;
23 
24     //p1 = &b; 错误，不允许向常量指针赋值
25     //cout<<p1<<" "<<*p1<<endl;
26     
27     const int * const p2 = &a;
28     cout<<p2<<" "<<*p2<<endl;
29     a = 100;
30     cout<<p2<<" "<<*p2<<endl;
31     //*p2 = 290;
32     //p2 = &b; 两者都不允许
33 
34     return 0;
35 }

输出：

0x7ffe6a0ecc34 5
0x7ffe6a0ecc30 10
0x7ffe6a0ecc34 5
0x7ffe6a0ecc34 5
0x7ffe6a0ecc34 100

 需要注意的是const int是可以修改的，见以下代码：

1 int main(){
2 
3     const int i = 0;
4     int *j = (int*)&i;
5     *j = 1;
6     cout<<i<<" "<<*j<<endl;
7 
8     return 0;
9 }

输出：

0 1

 

posted @ 2016-04-15 11:29  hu983  阅读(1136)  评论(0)  编辑  收藏  举报