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;
}