#include <iostream>
#include <math.h>

using namespace std;

int main()
{
    double a = 13.4565565326789;
    double b, c, d;
    cout<<a<<endl;
    b = floor(a * 10000.0000f) / 10000.0000f;       /*保留小數點後四位*/
    cout<<b<<endl;
    c = floor(a * 10000.0000f + 0.5) / 10000.0000f; /*保留小數點後四位，進行了四捨五入*/
    cout<<c<<endl;
    d = trunc(a*1000.0)/1000.0;                     /*保留小數點後三位*/
    cout<<d<<endl;

    return 0;
}