将十进制转换成二进制输出，递归写法

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void binary_num(int, int);
int main( int argc, char* argv[] )
{

    int a = 30;
    binary_num(a, sizeof(a) * 8);

    printf("\n");
    system("pause");
    return 0;
}

void binary_num(int a, int i)
{
    if (i > 1)
        binary_num(a >> 1, --i );
    if (a & 1)
        printf("1");
    else
        printf("0");
}