函数指针用法

示例一：

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 
 4 typedef  void *(*func_t)(void*, ...) ;
 5 func_t func;
 6 
 7 typedef struct set {
 8     func_t func;
 9     void * arg;
10 } set_t;
11 
12 
13 
14 void func1(int a)
15 {
16     printf("func----1	[%d]
", a);
17 }
18 
19 int func2(void)
20 {
21     printf("func----2
");
22 
23     return 0;
24 }
25 
26 
27 char* func3(int a)
28 {
29     while (a > 0)
30         printf("func----3	[%d]
", a--);
31 
32     return "123";
33 }
34 
35 
36 int func4(int a, int b)
37 {
38 
39     printf("func----4	[%d] %s [%d]
", a, ((a == b) ? "==" : ((a > b) ? ">" : "<")), b);
40 
41     return (a + b);
42 }
43 
44 void func5(int a, char* str, int b, float c)
45 {
46     c = 9.9;
47     printf("func----5	[%d] "%s" [%d] [%f]
", a, str, b, c);
48 
49 }
50 
51 void main()
52 {
53     set_t set_1;
54     int a = 3, b = 7;
55     int *intp;
56 
57     func = (void*)func1;
58     set_1.func = (void*)func1;
59 
60     (func)((void*)1);
61     (set_1.func)((void*)2);
62     printf("

");
63 
64 
65     func = (void*)func2;
66     set_1.func = (void*)func2;
67 
68     printf("func2 return: %d
", (func)((void*)1));
69     printf("func2 return: %d
", (set_1.func)((void*)2));
70     printf("

");
71 
72 
73     func = (void*)func3;
74     set_1.func = (void*)func3;
75 
76     printf("func2 return: %s
", (func)((void*)1));
77     printf("func2 return: %s
", (set_1.func)((void*)2));
78 
79 
80     func = (void*)func4;
81     set_1.func = (void*)func4;
82     printf("

");
83 
84     printf("func4 return: %d
", (func)((void*)9, (void*)50));
85 
86     printf("func4 return: %d
", (set_1.func)((void *)8, 3));
87     printf("

");
88 
89 
90     func = (void*)func5;
91     set_1.func = (void*)func5;
92 
93     (func)((void*)6, "hello world" ,66, (void*)6);
94     (set_1.func)((void*)5, "hi", 55, (void*)5);
95     printf("

");
96 
97     intp= (int*)func4;
98     printf("func4 return: %d
", ((func_t)intp)((void *)8, 3));
99 }

运行结果：

示例二：

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include <time.h>
 4 
 5 typedef  void *(*func_t)(void*, ...) ;
 6 func_t function;
 7 
 8 typedef struct set {
 9     func_t func;
10     int start_time;
11     int wait_time;
12 } set_t;
13 
14 int ex_time(int start, int timer)
15 {
16     if ((clock() - start) > timer)
17         return 1;
18     else
19         return 0;
20 }
21 
22 
23 #define CONNE(x,y)    (x##y)
24 #define SET_INIT(name) set_t name##set = {
25                             .func = (void*)name,
26                             .start_time = 0,
27                             .wait_time = 0
28                         };
29 
30 
31 #define SET_FUNC(name, t, ...)    
32 {
33     if (ex_time(name##set.start_time, t)) {
34         name##set.start_time = clock();
35         name##set.func((void*)__VA_ARGS__);
36     }
37 }
38 
39 void func1(int a)
40 {
41     printf("func----1	[%d]
", a);
42 }
43 
44 int func2(void)
45 {
46     printf("func----2
");
47     
48     return 0;
49 }
50 
51 
52 char* func3(int a)
53 {
54     while (a > 0)
55         printf("func----3	[%d]
", a--);
56     
57     return "123";
58 }
59 
60 
61 int func4(int a, int b)
62 {
63     
64     printf("func----4	[%d] %s [%d]
", a, ((a == b) ? "==" : ((a > b) ? ">" : "<")), b);
65     
66     return (a + b);
67 }
68 
69 void func5(int a, char* str, int b, float c)
70 {
71     printf("func----5	[%d] "%s" [%d] [%f]
", a, str, b, c);
72 }
73 
74 SET_INIT(func1);
75 SET_INIT(func4);
76 SET_INIT(func5);
77 
78 void main()
79 {
80     int func_addr = (int)func1;
81     float value = 6.6;
82     
83     /*强制转换为函数指针类型*/
84     ((void (*)(int))func_addr)(55);
85     
86     int start_time = clock();
87     while (!ex_time(start_time, 2000)) {
88         SET_FUNC(func1, 200, 10);
89         SET_FUNC(func4, 500, 88, 99);
90         SET_FUNC(func5, 500, 88, "hello", 99, value);
91     }
92 }

View Code

运行结果：