TCPL学习笔记：4-12以及4-13。关于使用递归的问题。

4-12.写一个函数itoa，通过递归调用将整数转换成为字符串。

 #include <stdio.h>
 #include <stdlib.h>
 void Itoa(int num, char * s);
 int main(void)
 {
     char s[];
     Itoa(, s);
     printf("The str now is %s", s);
     return ;
 }

 void Itoa(int n, char * s)
 {
     static int i = ;
     if(n < )
     {
         s[i++] = '-';
         s[i] = '\0';
         n = -n;
     }
     else
     {
         if(n/)
             Itoa(n/, s);
         s[i++] = '' + n%;
         s[i] = '\0';
     }

 }

编译结果为：The str now is 1234567
Process returned 0 (0x0)   execution time : 0.029 s
Press any key to continue.

4-13.编写一个递归版本的reverse(s)函数，用于将字符串s倒置。

 #include <stdio.h>
 #include <stdlib.h>
 void reversed(char * s, char * d);
 int main(void)
 {
     char s1[] = "wangcheng";
     char s2[];
     reversed(s1, s2);
     printf("The reversed string is : %s", s2);
     return ;
 }

 void reversed(char * s, char * d)
 {
     static int i = ;
     static int j = ;
     if(s[i+] != '\0')
     {
         i++;
         reversed(s, d);
     }
          d[j++] = s[i--];
          d[j] = '\0';
 }

 编译运行结果为：The reversed string is : gnehcgnaw
 Process returned  (0x0)   execution time : 0.009 s
 Press any key to continue.