从键盘读入一个数,然后进行运算
实现代码:
public static void main(String[] args) {
Scanner in=new Scanner(System.in);
int n ;
n=in.nextInt();
double sum=0.0;
for(int i=1;i<=n;i++)
{
sum=sum+1.0/i;
}
System.out.println(sum);
System.out.printf("%.2f",sum);//实现精准输出
}
2.
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in=new Scanner(System.in);
int n ;
n=in.nextInt();
double sum=0.0;
int sign=1;
for(int i=1;i<=n;i++)
{
sum=sign*sum+1.0/i;
sign=-sign;
}
System.out.println(sum);
System.out.printf("%.2f",sum);
}