[紧急求助]奇怪的输入格式！！

xd1198

小弟遇到一个很奇怪的输入格式问题，麻烦大家解答一下。代码如下：

1. 
   
2. [color=Red]#define OCTETRANGE "%3d%*1[-]%3d"
   
3. #define OCTET "%3d"
   
4. #define DOT "%*1[.]"
   
5. #define COMP "%7[0-9-]"  
   
6. #define REMINDER "%s"[/color]
   
7. static int
   
8. range(data, s, e)
   
9. char * data;
   
10. int * s;
    
11. int * e;
    
12. {
    
13. int convs;
    
14. int first, last;
    
15. 
    
16. [color=Red]convs=sscanf(data, OCTETRANGE, &first, &last);[/color]
    
17. if (convs != 2)
    
18. {
    
19.   /* it didn't work out, so we try converting it as
    
20.      an OCTET (xxx) */
    
21. [color=Red] convs=sscanf(data, OCTET, &first);[/color]
    
22.   if (convs != 1)
    
23.   {
    
24.    /* that didn't work out either, so it's not a range */
    
25.    return (-1);
    
26.   }
    
27.   else
    
28.   {
    
29.    /* we'll use these as loop ranges later */
    
30.    last = first;
    
31.   }
    
32. }
    
33. 
    
34. if((first < 0) || (first > 255) ||
    
35.     (last < 0 ) || (last  > 255))
    
36.             return (-1);
    
37.        
    
38. 
    
39. 
    
40. if(first > last)
    
41. {
    
42.   /* swap the two vars */
    
43. [color=Red] first ^= last;
    
44.   last  ^= first;
    
45.   first ^= last;[/color]
    
46. }
    
47. 
    
48. if(s)*s = first;
    
49. if(e)*e = last;
    
50. return 0;
    

复制代码

此段程序应该是判断ip方面的功能。红色字体都是小弟不明白的地方。麻烦大家指点一下。下面的程序是我写的测试程序.不知道为什么每次sscanf s[] 后，s就打印不出来。

1. 
   
2. #include<stdio.h>
   
3. #define OCTETRANGE "%3d%*1[-]%3d"
   
4. #define OCTET "%3d"
   
5. #define DOT "%*1[.]"
   
6. #define COMP "%7[0-9-]"  
   
7. #define REMINDER "%s"
   
8. 
   
9. main()
   
10. {
    
11.     char s[20]="2399defg[-] 2456";
    
12.         int a=1,b=1,c=3;
    
13.         c=sscanf(s, OCTETRANGE, &a, &b);
    
14.         printf("s=%s\n c=%4d a=%4d b=%4d\n",s,c,a,b);
    
15.         //s[20]="abcdefg";
    
16.         c=sscanf(s, COMP, &a, &b);
    
17.         printf("s=%s\n c=%4d a=%4d b=%4d\n",s,c,a,b);
    
18.         c=sscanf(s, OCTET, &a, &b);
    
19.         printf("s=%s\n c=%4d a=%4d b=%4d\n",s,c,a,b);
    
20.     printf(OCTETRANGE,5,6789,7);
    
21.     printf("\n****************************\n");
    
22.     printf(COMP,4444);
    
23.     printf("\n****************************\n");
    
24.     printf(OCTET,4);
    
25.     printf("\n****************************\n");
    
26.     printf(DOT,456);
    
27.     printf("\n");
    
28. }
    

复制代码

bookstack

man 3 scanf说的非常清楚阿：

%3d -- at most 3 character for decimal integer
%* -- ignore the next token
l[-] any character in [], i.e -

that is equvienlent to:
get at most 3 char for decimal integer, skip one -, then get at most 3 digit

so for the input as :
234-89, a = 234, b = 89
23-8900, a = 23, b = 890
... ...

xd1198

谢谢楼上的兄弟了。惭愧，我没有看scanf函数的man帮助。只是查了一下一个中文的c函数的帮助。没有找到这些。以后以后要养成先看man帮助的习惯了。