CODEWITHSUNDEEP
c++
John Lui
John Lui

Reputation: 1464

Missing decimals when printing

Below is some simple code I am working with:

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    float f = 1.66f;
    int d = (int)f;
    double g = (double)d;
    cout.precision(6);
    cout<<g<<"\n";
}

I want it to print 1.000000 but it prints only 1. But, even after upgradation of int to double, doesn't it automatically convert it to an integer value?

Upvotes: 2

Views: 2221

Answers (2)

Karlis Olte
Karlis Olte

Reputation: 353

Setprecision sets how precise the result has to, e.g.

std::cout << (1.f)/6 << std::endl;  // prints 0.166667
std::cout.precision(7);
std::cout << (1.f)/6 << std::endl;  // prints 0.1666667

But it does not require that 0's are printed out, consider:

std::cout.precision(5);
std::cout << 1.1110f << std::endl;      // prints 1.111
std::cout << 1.1111f << std::endl;      // prints 1.1111

And as coincoin suggests the solution to get 0's printed out is to use std::fixed!

Upvotes: 1

coincoin
coincoin

Reputation: 4685

You can add cout << std::fixed;

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    float f = 1.66f;
    int d = (int)f;
    double g = (double)d;
    cout.precision(6);
    cout << std::fixed;
    cout<<g<<"\n";
}

and you get 1.000000

Explanations (edit)

When you use std::fixed :

When floatfield is set to fixed, floating-point values are written using fixed-point notation: the value is represented with exactly as many digits in the decimal part as specified by the precision field (precision) and with no exponent part.

When you use the std::defaultfloat (the one you are using) :

When floatfield is set to defaultfloat, floating-point values are written using the default notation: the representation uses as many meaningful digits as needed up to the stream's decimal precision (precision), counting both the digits before and after the decimal point (if any).

That's why the following .000000 are considered irrevelant !
(If you had 1.00001 it would have been printed)

Upvotes: 7

Related Questions