C++ numbers aren't rounding correctly

Question

I am new to Stack Overflow, and programming in general. I am in a few classes for programming C++ and have come across an assignment I am having a bit of trouble with. This program is supposed to take fahrenheit and convert it to celsius. I have seen other programs, but could not find a duplicate to my particular problem. This is my code.

#include <iostream>
using namespace std;

int main()
{
    int fahrenheit;
    cout << "Please enter Fahrenheit degrees: ";
    cin >> fahrenheit;
    int celsius = 5.0 / 9 * (fahrenheit - 32.0);
    cout << "Celsius: " << celsius << endl;

    return 0;
}

So this is working great on 4 of the 5 tests that are run. It rounds 22.22 to 22 and 4.44 to 4 like it should, but when 0 F is put in, it rounds -17.77 to -17 instead of -18. I have been researching for about an hour and would love some help! Thank you.

Answer 1

Use std::round() instead of relying on the implicit conversion from double to int. Either that, or do not use conversion at all, show the temperature as a double.

EDIT: As others already pointed out, implicit conversion will not round but truncate the number instead (simply cut off everything after the decimal point).