C语言的const

C语言备忘：

#include<stdio.h>
int main()
{
    int _a = 1;
    int _b = 2;
    int _c = 3;
    const int* a = &_a;
    int* const b = &_b;

    //*a = 5;//ssignment of read-only location ‘*a’
    a = &_c;
    *b = 5;
    //*b = &_c;//ssignment makes integer from pointer without a cast
    printf("*a = %d\n",*a);
    printf("*b = %d\n",*b);
}

主要记录两种最常见写法：

(1)const int* a

指针a指向的地址里面内容不可变（只读），但是指针a可以指向其他的地址；

 //*a = 5;//ssignment of read-only location ‘*a’改变地址里面内容就会报错
 a = &_c;  //修改指针指向地址木有问题

 

(2)int* const b
指针b指向地址不可变，但是指针b指向地址里面内容可以修改

 *b = 5; //修改指针b指向地址里面内容木有问题
 //*b = &_c;//ssignment makes integer from pointer without a cast 修改指针b指向地址报错