作者csihcs (非天夜翔)
看板C_and_CPP
標題Re: [問題] 用遞迴做字串反轉..
時間Sat Jul 4 23:20:49 2009
※ 引述《gs9706 (神手)》之銘言：
: 題目是這樣的....
: Write a recursive function to reverse a string by C.
: For example, char a[ ] = "ABCDEFGH" ;
: printf (" %s \n", a); /* "ABCDEFGH" */
: reverse_string (a);
: printf (" %s \n", a); /* "HGFEDCBA" */
: 我怎麼想都想不出只傳一個位址參數的方法
: 又要遞迴.....
: 懇請解救~~~
int reverse_string(char *);
char str[] = "123456789";
call time | reserve c call next
str value |
main:
123456789 |
a:
123456789 | 1
b:
123456789 | 2
c:
123456789 | 3
d:
123456789 | 4
e:
123456789 | 5
f:
123456789 | 6
g:
123456789 | 7
h:
123456789 | 8
return time| back time after copy after put c return back
str value | c str value
i:
123456789 |
h:
123456798 | 8
123456789 123456799 123456798
g:
123456987 | 7
123456798 123456988 123456987
f:
123459876 | 6
123456987 123459877 123459876
e:
123498765 | 5
123459876 123498766 123498765
d:
123987654 | 4
123498765 123987655 123987654
c:
129876543 | 3
123987654 129876544 129876543
b:
198765432 | 2
129876543 198765433 198765432
a:
987654321 | 1
198765432 987654322 987654321
main:
987654321 |
987654321
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 211.74.9.2
1F：→ csihcs:if(!str || str[0] == '\0') return 0; 07/04 23:24
2F：→ csihcs:else if(str[1] == '\0') return 1; 07/04 23:25
3F：→ csihcs:... ; i = reverse_string(str); ... ; return i+1; 07/04 23:26
4F：推 ledia:len = strlen(str); if(len <= 1) return; 07/06 01:47
5F：→ ledia:swap(str[0], str[len-1]); 07/06 01:47
6F：→ ledia:backup str[len-1]; str[len-1] = '\0'; 07/06 01:48
7F：→ ledia:reverse_string(str+1); 07/06 01:48
8F：→ ledia:restore str[len-1]; 07/06 01:48
9F：→ ledia:好醜 ._. 07/06 01:49