1.指针常量
int * const p=null;
2.常量指针
int const *p = null;
3.指针和 const 谁在前先读谁 ;
*
象征着地址,const
象征着内容;
谁在前面谁就不允许改变。
改变指针b指向地址的内容
int main()
{
int a = 2;
int const *b = &a;
*b = 3; //报错:expression must be a modifiable lvalue
printf("albert:%d\n",a);
}
#改变指针b的指向
int main()
{
int a = 2;
int b = 3;
int const *c = &a;
printf("albert:%p\n", c);
c = &b;
printf("albert:%p\n",c);
}
案例2:指针指向的地址不可以重新赋值,但内容可以改变。
int main()
{
int a = 2;
int b = 3;
int *const c = &a;
printf("albert:%p\n", c);
c = &b; //报错:expression must be a modifiable lvalue
printf("albert:%p\n",c);
}
int main()
{
int a = 2;
int b = 3;
int *const c = &a;
*c = 4;
printf("albert:%d\n",*c); //4
}
指针和函数
void swap(int *a,int *b){
int tmp = *a;
*a = *b;
*b = temp;
}
用途:
1. 改变参数本来的值
2. 用于返回更多的值
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