#include <iostream>
#include <iomanip>
using std::cout;
using std::endl;
int main()
{
double a = 20;
double b = 100.0;
double pi = 3.1416;
std::cout.precision(5);
std::cout << std::showpoint << a << " : " << b << " : " << pi << endl;
std::cout << std::noshowpoint << a << " : " << b << " : " << pi << endl;
return 0;
}
/*
run:
20.000 : 100.00 : 3.1416
20 : 100 : 3.1416
*/