/* Filename: HW7.c*/
/* This program solves the quadratic formula */


/******************************************************************
 *                                                                *
 * Programmer: Matthew Glynn                                      *
 * Date : 03/21/2007                                              *
 * Section Number: B36                                            * 
 * Filename: HW7.c                                                *
 * Description: This program solves the quadratic formula		  *
 * and checks for invalid input                                   *
 ******************************************************************/

/* libraries to be used */
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <math.h>

/* Declare functions */

void readcoefficients ( int *a, int *b, int *c );
void factors( int *a, int *b, int *c );
void quadraticcoefficient( int *pointer );


int main ( void )


{/* start main */
	int valuea, valueb, valuec;
	int *a=&valuea, *b=&valueb, *c=&valuec;

	printf("\n This is a quadratic-equation calculator\n");
	printf("\n     Format:   ax^2  +  bX  +  c \n\n");

	readcoefficients( a, b, c );

	factors( a, b, c );
	return 0;
}/* end main */



/******************************************************************
 *                                                                *
 * Programmer: Matthew Glynn                                      *
 * Name: readcoefficients                                         *
 * Function: This function prints the main menu of the program.   *
 * Algorithm: uses printf to display messages and the             *
 * quadraticcoefficient function								  *
 * Input: int *a, int *b, int *c                                  *
 *                                                                *
 ******************************************************************/

void readcoefficients( int *a, int *b, int *c )

{
	printf("\n Enter the value of a: ");
	quadraticcoefficient( a ); /*a becomes quadraticcoefficient pointer after function is ran*/


	printf("\n Enter the value of b: ");
	quadraticcoefficient( b );

	printf("\n Enter the value of c: ");
	quadraticcoefficient( c );


}

/******************************************************************
 *                                                                *
 * Programmer: Matthew Glynn                                      *
 * Name:  factors                                                 *
 * Function: This function solves the quadratic formula		      *
 * and checks for invalid input                                   *
 * Algorithm: uses pointers s, b, and c in the quadratic formula  *
 * Input: int *a, int *b, int *c                                  *
 *                                                                *
 ******************************************************************/

void factors(int *a, int *b, int *c)

{
	double disc, X1, X2;

			disc = (*b)*(*b) - 4*(*a)*(*c);

			if(disc >=0 )
			{

				disc = sqrt ( disc );/*works*/
				X1 = (-(*b) + disc ) / 2*(*a);
				X2 = (-(*b) - disc ) / 2*(*a);
				
				printf("\n The roots are:\n\n\t%1f\n  and\n\t%1f\n\n", X1, X2);
			}

			else
			{
				printf("\n The roots are a complex conjugative pair: \n");

				printf("\n\t%d + %c%.01f", -(*b), 251, disc);
				printf("\n\t--------------------\n\t\t%d\n and \n",2*(*a));

				printf("\n\t%d + %c%.01f", -(*b), 251, disc);
				printf("\n\t--------------------\n\t\t%d\n and \n",2*(*a));

			}
			return 0;
}

/******************************************************************
 *                                                                *
 * Programmer: Matthew Glynn                                      *
 * Name: quadraticcoefficient                                     *
 * Function: brings in coefficients and checks for bad input      *
 * Algorithm: This function puts coefficients as pointers         *
 * Input: int *pointer                                            *
 ******************************************************************/
void quadraticcoefficient ( int *pointer )
{ 
	char array1[10];
	int number, counter, coefficient;
do
		{ 
			gets( array1 );/*get input from user*/
			number = 1;
			for( counter = 0; array1[counter] != '\0'; counter = counter + 1 )
			{
				if( !isdigit( array1[counter] )) /*check for if input is digit from 1-10*/

				{
					number = 0;
						break;
				}
			}
			if( number == 0 ) {
				printf("\n\t Error: bad input; Please try again\n\n\t\tvalue:");
			}
			else {
				coefficient = atoi(array1); /*use array to integer*/
			}

		}while ((number == 0)||(coefficient ==0));

		*pointer = coefficient;

}


/*************************************************************************
 * Programmed by: Matt Glynn                                             *
 *************************************************************************/