putchar('0'+((unsigned)(x&(1<<(n-1)))>>(n-1)));//31左移1位再移回去什么意思？
#include<stdio.h>void printb(int,int);int main(){int x;printf("Input number:");scanf("%d",&x);printf("number of decimal form:%d\n",x);printf(" it's binary form:");printb(x,sizeof(int)*8); /*x:整数 sizeof(int):int型在内存中所占的字节数sizeof(int)*8:int型对应的位数*/putchar('\n');}void printb(int x,int n){if(n>0){putchar('0'+((unsigned)(x&(1<<(n-1)))>>(n-1))); /*输出第n位*/printb(x,n-1); /*归调用，输出x的后n-1位*/}}