递归算法的学习

/*淮南师范学院 电子工程学院 夏健钧 2017/3/25*/
/* binary.c -- 以二进制形式打印正整数*/
#include<stdio.h>
void to_binary (unsigned long n);

int main(int argc, const char *argv[])
{
 unsigned long number;
 printf("Enter an integer (q to quit): \n");
 while (scanf ("%lu",&number) == 1)
 {
  printf("Binary equivalent: ");
  to_binary(number);
  putchar ('\n');
  printf("Enter an integer (q to quit): \n");
 }
 printf("Done. \n");
 
 return 0;
}

void to_binary (unsigned long n ) /* 递归函数 */         
{                 /*利用递归 先调用 最后出的特点 巧妙的打印二进制数*/  
 int r;
 r = n %2;
 if(n > 2)
  to_binary (n/2);
 putchar(r == 0 ? '0' : '1');
 return ;
}