整数与其他进制数之间的转换

编写一个函数itob（int n,char s[], int b）,将整数n转换为以b进制的数。保存到s中。
#include <stdio.h>
 
void reverse(char*left, char *right)
{
         while(left < right)
         {
                   chartmp = *left;
                   *left = *right;
                   *right = tmp;
                   left++;
                   right--;
         }
}
void itob(int n, char s[], int b)
{
                   char*start;
                   char*end;
                   start = s;
                   while(n)
                   {
                            if (b <= 10)
                                     *s = (n %b) + '0';
                            else if (b == 16)
                                     *s = "0123456789abcdef"[n % b];
                            s++;
                            n /= b;
                   }
                   *s = '\0';
                   end = s - 1;
                   reverse(start, end);
}
int main()
{
         int num= 1234;
         chararr[20];
         int b =0;
         scanf("%d",&b);
         itob(num, arr, b);
         printf("%s\n",arr);
         system("pause");
         return0;
}