#include<stdio.h>
main()
{
    int y,i=0,t=0,j,k,g=0,m;
    int a[10],b[10];
    double x,z,s=0.0;
    printf("please input the number:\n");
    scanf("%f",x);
    y=(int)x;
    while(y)
    {
        a[i]=y%2;
        i++;
        y=y/2;
    }
    for(j=i;j>=0;j--)
        t=10*t+a[j];
    printf("the sum1 is %d\n",t);
    z=x-(int)x;
    for(k=1;k<=20;k++)
    {
        z=z*2;
        b[g]=(int)z;
        z=z-(int)z;
        g++;
    }
    while(b[g]==0)
    {
        g--;
    }
    for(m=g;m>=0;m--)
        s=s*0.1+b[g];
    printf("the sum2 is %f\n",s);
}

  scanf("%lf", &x);

printf("the sum2 is %lf\n",s);

double类型输入输出时，要用%lf, scanf给变量赋值时，传的是地址

谢谢