1 #include <stdio.h>
2 #include <string.h>
3
4 typedef struct node
5 {
6 int next;
7 int data;
8 }*Node;
9
10 void modify(Node l)
11 {
12 printf("l = %d, &l = %u\n",l,&l);
13 l->data = 1;
14 l->next = 1;
15 (*l).data = 10;
16 (*l).next = 100;
17 }
18
19 Node MM(Node l)
20 {
21 l = new node;
22 l->data = 2;
23 l->next = 2;
24 return l;
25 }
26
27 void M(Node *l) //二维指针
28 {
29 (*l) = new node;
30 (*l)->data = 12;
31 (*l)->next = 12;
32 }
33 void fun1(char *pa) //相当于传值
34 {
35 //相当与char *tmp = pa;
36 printf("&pa = %u pa %d pa = %s\n", &pa, pa,pa);
37 pa = "ni,mei"; //只是更改了tmp的值
38 printf("%u %d %s\n", &pa, pa,pa);
39 }
40
41 void fun2(char **pa) //传递pa的地址
42 {
43 *pa = "nimie"; //指向pa char *指针
44 }
45
46 void int1(int *p)
47 {
48 *p = 100;
49
50 }
51
52 int main( )
53 {
54 //下面这个等价
55 const char *p;
56 char const *q;
57 // "hello" 为字符串常量 const char [5]
58 char *c1 = "hello";
59 char *tt;
60 tt = c1;
61 // tt为char *指针
62 // *tt 为char 指向内存单位为tt的第一个字符
63 tt = "wawa";
64 char *const l = tt; //对与这种只能在初始化时赋值
65 const char * const m = "haha"; //指向const对象的const指针
66 char c2[20] = "world";
67 char c3[15];
68 // 不能这样赋值， c3 = "haha",
69 p = c1;
70 q = c2;
71 printf("%s\n%s\n%s\n%s\n",p,q,m,l);
72
73 int st = 10;
74 int *pp = &st;
75 printf("int %u %d\n",pp, *pp);
76
77 char *pa = "now";
78 printf("&pa = %u pa = %d %s\n",&pa, pa, pa);
79 printf("函数1:\n");
80 printf("修改之前:%s\n",pa);
81 fun1(pa); //这里相当于值传递
82 printf("修改之后:%s\n", pa);
83
84 printf("函数2:\n");
85 printf("修改之前:%s\n",pa);
86 fun2(&pa);
87 printf("修改之后:%s\n", pa);
88
89 Node ps = new node;
90 printf("ps = %d, &ps = %d\n",ps,&ps);
91 /* ps 只是一个指向Node的指针，没有申请内存
92 ps->data = 2;
93 ps->next = 2;
94 */
95 printf("%d %d\n",ps->data,ps->next);
96 modify(ps);
97 printf("%d %d\n",ps->data,ps->next);
98
99 Node pq;
100 //printf("%d %d\n",ps->data,ps->next);
101 pq = MM(pq);
102 printf("%d %d\n",pq->data,pq->next);
103
104 //需要用二维指针
105 Node pl;
106 M(&pl);
107 printf("%d %d\n",pl->data,pl->next);
108
109 int *ll = &st;
110 printf("ll = %d\n",*ll);
111 int1(ll);
112 printf("ll = %d\n",*ll);
113 return 0;
114 }
