Quadratic Using pointers

[rrreeefff]

Hello!

I am working on a program that calculates the quadratic formula using pointers. Here is as far as I have gotten:

#include "stdafx.h"
#include "stdio.h"
#include "math.h"

/*Function Prototype*/
 
int quad_1(double a, double b, double c);
int quad_2(double a, double b, double c);


int main (void)
{
	double result1,result2;
	double a,b,c;

	printf("the equation is ax^2+bx+c=0,enter a value for a\n");
	scanf("%lf",&a);
	printf("enter a value for b\n");
	scanf("%lf",&b);
	printf("enter a value for c\n");
	scanf("%lf",&c);
	result1= quad_1(a,b,c);
	result2= quad_2(a,b,c);
printf("result here %f\n",result1);
printf("result here %f\n",result2);
	return 0;
}
int quad_1(double a,double b, double c)
{
	double x1;
	if(((b*b)- 4*a*c >= 0)&& (a!=0))
	{
		x1 = sqrt((b * b) - (4 * a * c));
        x1 = (-b + x1) / (2 * a);
		return x1;
	}
    
	else return -1;
}
int quad_2(double a,double b, double c)
{
	double x2;
	if(((b*b)- 4*a*c >= 0)&& (a!=0))
	{
		x2= sqrt((b * b) - (4 * a * c));
		x2 = (-b - x2) / (2 * a);
		return x2;
	}
	else return -1;
}

[Dino]

Good for you. Did you have a question?

[tabstop]

You can't return a double from a function that's designated as returning int, like quad_1. Are you supposed to give a fourth argument (specifically double *result) for the result to be stored in?

[rrreeefff]

yes, sorry I forgot to put my question. I do not think my pointers are correct because I need an output and it just seems like a function

[rrreeefff]

yes, I need a place where results are stored!

[tabstop]

So pass it in.

int quad_1(double a, double b, double c, double *result);

(Or, if you're Elysia,

int quad_1(double a, double b, double c, double* result);

)

[zacs7]

or

int quad_1(double a, double b, double c, double * result);

That way everyone loves you!

[rrreeefff]

where would I put that in the function prototype?

[tabstop]

That is the function prototype.

[rrreeefff]

That is the function prototype.

what about quad2?

[tabstop]

Why wouldn't it be exactly the same?

[rrreeefff]

i am asking because (26) : error C2660: 'quad_1' : function does not take 3 arguments
quad_2' : function does not take 3 arguments

[tabstop]

No, they don't. So put 4 freakin' arguments inside the parentheses when you call the function already.

[iMalc]

Well that was interesting ... A question about pointers in a program that doesn't contain a single pointer variable! Is there actually something about pointers you'd like to ask us?

The good news is that there's plenty of room for optimisation .

[nonoob]

if the functions simply returned double, it would work, right?

double quad_1(double a,double b, double c)

... in the prototypes as well as the actual function headers.
But the OP's question seemed to imply this may be a pointers exercise. So the four argument way is the solution. Until it's made clearer what the parameters of the homework is.