quadratic formula via the non-void function

[cmiller9732]

Your main function should acquire the values for a, b, and c and report the results of the function call ....where have I went wrong please help! thanks

[Daleth]

You never initialize the variable x or do not have any method to assign it a value.

[cmiller9732]

the assignment says to only acquire values for a b c not x idk what to do

[Daleth]

Well, if for example you want to display a list of results from the calls f(x_o) to f(x_n), then you can use a for loop to pass varying values of x:

const int max = 10;   //Arbitrary maximum number
for(int x= 0; x< max; x++){
   std::cout << answer(a,b,c,x) << '\n';
}

However, this all depends on how you are supposed to display the return values.

[cmiller9732]

ok I was completly wrong from the start here is what I have now

#include "stdafx.h"
#include <iostream>
#include <cmath>
using namespace std;



bool quad(int, int, int, double, double);
	
//int _tmain(int argc, _TCHAR* argv[])
int main()
{
int a,b,c;
double r1, r2;

cout << "enter a number";
cin >> a;
cout << "enter another number";
cin >> b;
cout << "enter the last number";
cin >> c;
if(quad(a,b,c,r1,r2))
{
	cout << "solution found:"<< r1 << "," << r2 << endl;
}
else
{
	cout << " no solution!\n";
}
return 0;
}
bool quad( int a, int b, int c, double r1, double r2)
{
	bool valid = true;
	if(b*b-4*a*c>0)
	{
		valid = false;
	}
	else
	{
		r1=(b + sqrt * b-4*a*c))/(2*a);
		r2=(b - sqrt *b-4*a*c))/(2*a);
	}
	return valid;
}

[Daleth]

bool quad( int a, int b, int c, double r1, double r2)

In your main function, you wanted to print out the new values of r1 and r2 after passing them to the quad function. However, you are passing by value, which means that copies of r1 and r2 are modified, not the original variables. Pass r1 and r2 by reference instead.

On a side note, your else statement in your main function is not entirely accurate. It should be "No real solution." :)

Edit:

r1=(b + sqrt * b-4*a*c))/(2*a);
r2=(b - sqr t *b-4*a*c))/(2*a);

You made a typo with the asterisks after "sqrt," the second b should be squared, and there is an extra space.

[cmiller9732]

what should I do to fix this?

[Daleth]

Have you learned how to use reference (&) variables? An example of a function that passes by reference is void funct(char &ref){/*...*/}

Also, I noticed this bit:

if(b*b-4*a*c>0)
	{
		valid = false;
	}

You may want to check your condition.

[cmiller9732]

these are the errors im getting

1>c:\users\cameron\documents\visual studio 2010\projects\cdfm21\cdfm21\cdfm21.cpp(34): error C2668: 'pow' : ambiguous call to overloaded function
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(583): could be 'long double pow(long double,int)'
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(535): or       'float pow(float,int)'
1>          c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(497): or       'double pow(double,int)'
1>          while trying to match the argument list '(int, int)'
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

[Daleth]

May you post your updated code?

[cmiller9732]

I cannot use a void function in the assignmet

#include "stdafx.h"
#include <iostream>
#include <cmath>
using namespace std;



bool quad(int, int, int, double, double);
	
//int _tmain(int argc, _TCHAR* argv[])
int main()
{
int a,b,c;
double r1, r2;

cout << "enter a number";
cin >> a;
cout << "enter another number";
cin >> b;
cout << "enter the last number";
cin >> c;

if(quad(a,b,c,r1,r2))
{
	cout << "solution found:"<< r1 << "," << r2 << endl;
}
else
{
	cout << " no real solution!\n";
}
return 0;
}
bool quad( int a, int b, int c, double r1, double r2)
{
	bool valid = true;
	if( b*b-4*a*c > 0)
	{
		valid = false;
	}
	else
	{
		r1=(-b + sqrt * b-4*a*c))/(2*a);
		r2=(-b - sqrt *b-4*a*c))/(2*a);
	}
	return valid;
}

[Daleth]

	if( b*b-4*a*c > 0)
	{
		valid = false;
	}
	else
	{
		r1=(-b + sqrt * b-4*a*c))/(2*a);
		r2=(-b - sqrt *b-4*a*c))/(2*a);
	}

I am not sure about your "ambiguous pow called" issue, but perhaps it stems from the assignment lines. "sqrt" is a function, so I believe you meant sqrt(b*b-4*a*c).

Also, please address your if condition. The function will return false even if a real solution exists.