来看看我写的代码吧

#include<iostream>
#include<stdio.h>
using namespace std;
int main(){
    float s;
    int a,b,c,d,e;
    cin>>s;
    int ss=s*10;
    a=ss/1000;
    ss=ss%1000;
    b=ss/100;
    ss=ss%100;
    c=ss/10;
    d=ss%10;
    printf("%.3f",d+c*0.1+b*0.01+a*0.001);
    return 0;
}