用一个 指针 指向 指针
1 int num=10;
2 int *p1=#
3 int *p2=p1;
4
5 printf("num1:%d\n",num);
6 printf("*p1-1:%d\n",*p1);
7 printf("*p2-1:%d\n",*p2);
8
9 *p1=100;
10 printf("num2:%d\n",num);
11 printf("*p1-2:%d\n",*p1);
12 printf("*p2-2:%d\n",*p2); 运行结果如图：
逻辑结构如图：
用一个 指针的指针 指向 指针
1 int num=10;
2 int *p1=#
3 int **p2=&p1;
4
5 printf("num-add:%d\n",&num);//正确参数应该用%p来输出地址，这里为了简洁用%d
6 printf("p1-add:%d\n",&p1);
7 printf("p2-add:%d\n",&p2);
8 printf("p2:%d\n",p2);//p1的地址
9 printf("*p2:%d\n",*p2);//p1的地址上的值->num的地址
10 printf("**p2:%d\n\n",**p2);//num的地址上的值->num的值
11
12 printf("num1:%d\n",num);
13 printf("*p1-1:%d\n",*p1);
14 printf("**p2-1:%d\n",**p2);
15
16 *p1=100;
17 printf("num2:%d\n",num);
18 printf("*p1-2:%d\n",*p1);
19 printf("**p2-2:%d\n",**p2);