Decimals are all zeros?

[thekingofbs]

I've heard that there is an assignment in school that says you have to write a code for the quadratic equation. I decided to try my hand at it. The equation seems to be losing decimals some where in the equation.

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


int main ()
{
    int a,b,c,d,e,f,g,j;
    double h;
    cout << "Enter a";
    cin >> a;
    cout << "Enter b";
    cin >> b;
    cout << "Enter c";
    cin >> c;
    system("PAUSE");
    d = b-2*b;
    e =(b*b)-(4*a*c);
    f = sqrt(e);
    g = f + d;
    h = g/(2*a);
    cout.precision(5);
    cout << fixed << "If you add, x = "  << h <<endl;
    system("PAUSE");
    f = sqrt(e);
    g = f - d;
    h = g/(2*a);
    cout << "If you subtract, x = " << h << endl;
   system("PAUSE"); 
  return 0;  
        
}

When I get the answer, the only true value are the number before the decimal point. After that, they are all zeros.

[Gumbercules]

You're doing integer arithmetic. try changing all your ints to doubles.

[thekingofbs]

Thanks, it worked.
I have a new problem though. It's not showing if the value is negative. I tried making it

int main ()
{
    double j,a,b,c,d,e,f,g,h;
    cout << "Enter a";
    cin >> a;
    cout << "Enter b";
    cin >> b;
    cout << "Enter c";
    cin >> c;
    system("PAUSE");
    d = b-2*b;
    e =(b*b)-(4*a*c);
    f = sqrt(e);
    g = f + d;
    h = g/(2*a);
    cout.precision(5);
    if
    (h < 0)
    {cout << "If you add, x = -"  << h <<endl;
     system("PAUSE");
    f = sqrt(e);
    g = f - d;
    h = g/(2*a);
    cout << "If you subtract, x = -" << h << endl;
   system("PAUSE"); 
  return 0; } 
    if
    (h >= 0)
    {cout << fixed << "If you add, x = "  << h <<endl;
    system("PAUSE");
    f = sqrt(e);
    g = f - d;
    h = g/(2*a);
    cout << "If you subtract, x = " << h << endl;
   system("PAUSE"); 
  return 0; } 
        
}

but for some reason, the program itself is only dealing in positives.

[eker676]

Forget the 20 local variables you have. Simplicity is the key

#include <iostream>
#include <cmath>

using namespace std;


int main ()
{
	double a, b, c;
	
	double answer = 0;
	
	double discriminant = 0;
	
	cout << "Enter a";
	cin >> a;
	
	cout << "Enter b";
	cin >> b;
	
	cout << "Enter c";
	cin >> c;
    
	// calculate the discriminant
	discriminant = pow(b, 2) - (4 * a * c);

	// d < 0 = no roots, d = 0 = 1 root, d > 0 = 2 roots
	if(discriminant < 0)
	{
		cout << "No real roots, skipping calculation.\n";
	}
	else if(discriminant == 0)
	{
		cout << "1 real root, calculating value...\n";
		answer = (-b) / (2 * a);
		cout << "Answer = " << answer << endl;
	}
	else if(discriminant > 0)
	{
		cout << "2 real roots, calculating values...\n";
		answer = (-b + sqrt( (pow(b, 2) - (4 * a * c))) ) / (2 * a);
		cout << "Answer+ = " << answer << endl;
		
		answer = (-b - sqrt( (pow(b, 2) - (4 * a * c))) ) / (2 * a);
		cout << "Answer- = " << answer << endl;
	}

	system("pause");

	return 0;
        
}