Rouding and truncating a variable

[JHus00]

//function example 
#include <iostream>
#include <cmath>
using namespace std;



float cutoff(float& windchill)
{

	int z;
	z = (int)(windchill + 0.5);
	return(z);

}

float calculate (int& t, int& v)
{

	float windchill;
	windchill = 35.74 + (0.6215 * t) - 35.75 * pow(v,0.16) + 0.4275 * t * pow(v,0.16);
	return(windchill);

} 

void input (int& temp, int& windspeed)
{

	cout << "Enter the temperature: "; 
	cin >> temp;
	cout << "\nEnter the windspeed: "; 
	cin >> windspeed;

}


int main ()
{

	int temp, windspeed, z;
	float windchill;

	input(temp, windspeed);
	cout << "\nTemp is: " << temp << "\nWindspeed is: " << windspeed;
	calculate(temp,windspeed);
	cout << "\n\nWindchill is: " << cutoff(windchill) << endl << endl;

	return 0;
}

I need some help figuring out why when 'windchill' is returned to main Im getting the value "-1.07374e+008". When I want to just add 0.5 and truncate the decimal. Its doing this for anything I enter

Thanks,
Jordan

Edit: yes, I realize I spelled rounding wrong :p

[Fbody]

I would suggest changing all of your floating point variables and returns from float to double. There is a difference in how floats and doubles are handled in the system and there is a difference in precision. You may be getting some inaccuracies because of the mingling of the 2 types. There are 2 reasons:
1. The function pow() accepts and returns double values.
2. The compiler assumes that you have entered a double if you use a decimal point, unless you put an 'f' suffix on your number.

float fMyDecimal = 0.0;

fMyDecimal = 15.2;
//this is assigning a double to a float, there could be errors
//the compiler is also likely to at least return a warning about truncation

fMyDecimal = 15.2f;  //notice the 'f'
//this is assigning a float, there should be no data loss or errors

[wingless]

Now it's time to do duck-debugging!

Explain what this line

calculate(temp,windspeed);

and this function

float calculate (int& t, int& v)
{

	float windchill;
	windchill = 35.74 + (0.6215 * t) - 35.75 * pow(v,0.16) + 0.4275 * t * pow(v,0.16);
	return(windchill);

}

do.

[HealBrains]

It looks like you're using an uninitialised variable...

You never use the float 'windchill' until you add 0.5 to it. So basically you're adding 0.5 to some random number.