Thread: Why is this program converting to integers

Code:

// This program converts Celcius to Fahrenheit

#include <iostream.h>
#include <iomanip.h>

void main(void)
{
	float Celcius, Fahrenheit;
	cout << "Please enter a a temperature in Celcius: ";
	cin >> Celcius;

	Fahrenheit = ((9.0/5.0)*Celcius) + 32;

	cout.setf(ios::fixed);
	cout.precision(1);
	cout << endl;

	cout << "The temperature you entered is " << Fahrenheit << " degrees Fahrenheit." << endl << endl;

}

Note the Fahrenheit calculation. If I use the following, it simply doesn't work:
Fahrenheit = ((9/5)*Celcius) + 32;

It's taking the 9/5 and converting it to an integer value of 1. I had to use the decimal to get it to work. Is this a feature of my compiler? - Visual C++ 6.0

Why would it do this?

9/5 comes out to one because it sees the 9 and the 5 and goes "ok those are integers" and follows the normal integer division rules.

So by saying 9.0/5.0 it sees the 9.0 and the 5.0 and goes "ok those are doubles" and follows the normal double division rules.

Originally Posted by Thantos

9/5 comes out to one because it sees the 9 and the 5 and goes "ok those are integers" and follows the normal integer division rules.

So by saying 9.0/5.0 it sees the 9.0 and the 5.0 and goes "ok those are doubles" and follows the normal double division rules.

Thanks! I figured that's what it was doing, but I just can't fathom why they would make it that way. Is this normal? I would imagine it would have promoted those to floating points since Celcius is a float as well.

So many things to learn and understand.......

Thanks again for helping me out on this one.....

It is normal. Most compilers will actually do the division during compile time and store the result and during run time multiple it by Celcius.