Double sum problem in output, C++, HELP

Question

Hello.
I have the code bellow where I have a double variable and I get another from user input. I can't understand why do I get a result in form of "10" instead of "10.0" in the console output. Without declaring another variable for their sum. Please help!

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#include <iostream>
using namespace std;

int main() {
int i = 4;
double d = 4.0;
string s = "I can't understand why do I get 8 instead of 8.0 in the output for d+d2 ";

int i2;
double d2;
string s2;

cin>>i2;
// i2=12;
cin>>d2;
// d2=4.0;
cin>>s2;
// s2="Sleeping is my SUPERPOWER!";

cout<<i+i2<<endl;
cout<<d+d2<<endl;
cout<<s+s2<<endl;

return 0;
}

Answer 1

Because the extra ".0" is redundant information.

If you want to make it visible, include the <iomanip> header, and then use std::setprecision(2) followed by std::fixed to always show 2 decimal places:

std::cout << std::setprecision(2) << std::fixed << d + d2 << std::endl;

"setprecision" sets the minimum number of decimal places to show, and "fixed" forces it to always show that many decimal places, even if it's just 0.

Answer 2

Thank you very much :)
Sometimes there are these details I struggle with