有限状态机在C语言编程中的各种应用

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
//使用switch/case或者if/else实现的基于状态机(FSM)的密码锁
//只有正确输入密码 2479 才能解锁 
#include <stdio.h>  
#include <stdlib.h>  
#include <string.h>   

typedef enum{   
	STATE0 = 0,   
	STATE1,   
	STATE2,  
	STATE3,   
	STATE4,  
}STATE;
  

int main()   

{   
	char ch; 
	STATE current_state = STATE0;    
	while(1){   
		printf("In put password:");   
		while((ch = getchar()) != 'n')
		{   
			if((ch < '0') || (ch > '9'))
			{   
				printf("Input num,ok?/n");   
				break;   
			}   
			switch(current_state){   
			case STATE0:   
				if(ch == '2')   current_state = STATE1;   
				break;   
			case STATE1:   
				if(ch == '4')   current_state = STATE2;   
				break;   
			case STATE2:   
				if(ch == '7')   current_state = STATE3;   
				break;   
			case STATE3:   
				if(ch == '9')   current_state = STATE4;   
				break;   
			default:   
				current_state = STATE0;   
				break;   
			}   
		}   //end inner while 

		if(current_state == STATE4){   
			printf("Correct, lock is open!n");   
			current_state =   STATE0;
			
		}else
		{
			printf("Wrong, locked!n");   
			current_state =   STATE0;
			
		}
		break;
	}   
	return 0;   

} 
//代码摘自http://blog.csdn.net/qp120291570/article/details/8634582 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
//使用函数指针实现的基于状态机(FSM)的密码锁
//只有正确输入密码 2479 才能解锁 
#include <stdio.h>  
//这个秘密锁的密码是xxxx2479,就是说最后4位是2479,前面若干为为0~9里的数字,也可没有 
#include <stdlib.h>  
#include <string.h>   

//定义锁事件处理函数的函数指针类型
typedef void (*lock_func_temp)(char c);
typedef lock_func_temp (*lock_func)(char c);
lock_func state;

//函数声明队列 
//列出来,交叉引用才不会报错 
lock_func init_state(char ch);
lock_func state1(char ch);
lock_func state2(char ch);
lock_func state3(char ch);
lock_func state4(char ch);

//初始状态 
lock_func init_state(char ch)
{
    if ((ch < '0') || (ch > '9'))
        return NULL;	
    else
    	return state1(ch); //这里还必须得有参数,不然就会漏处理一个字符 
}

//状态1 
lock_func state1(char ch)
{
	if (ch == '2')
	{
		return state2;		
	} else 
	{
		return init_state;
	}
}

//状态2 
lock_func state2(char ch)
{
	if (ch == '4')
	{
		return state3;		
	} else 
	{
		return init_state;
	}	
}

//状态3 
lock_func state3(char ch)
{
	if (ch == '7')
	{
		return state4;		
	} else 
	{
		return init_state;
	}
}

//状态4 
lock_func state4(char ch)
{
	if (ch == '9')
	{
		printf("Correct, lock is open!n"); 
		return NULL;		
	} else 
	{
		return init_state;
	}
}

//结束状态是NULL
//就是通过 return NULL;表达的结束状态. 
 
//状态转换在这里 
void lock_handle (void)
{
	char ch;
	state = init_state;
	while (state)
	{
		ch = getchar();
		state = (*state)(ch);
	}
} 

 
int main()   
{     	
	lock_handle();
}