Calculate the real roots of a quadratic equation

[beanryu]

Please Help!

I designed this "PROGRAM"! TO calculate the real roots of a quadratic equation...

but the compiler miracle C kept saying there's something wrong around the "if" word... saying "unrecognised types in comparison"
it seem SO FINE to me... what is wrong?!

#include <stdio.h>
#include <math.h>

int main(void)
{
/* Declare variables. */
double a,b,c,d,e,f;

printf("This program computes the real roots of a quadratic equations.\n");
printf("(recall that the general form of quadratic equation is ax^2+bx+c where a, b and c are canstants)\n");

printf("please enter the first coefficient.\n");
scanf("%f", &a);
printf("%f\n",a);

printf("please enter the second coefficient.\n");
scanf("%f", &b);
printf("%f\n",b);

printf("please enter the third coefficient.\n");
scanf("%f", &c);
printf("%f\n",c);

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

if(f<0)
printf("roots are not real.\n");

else
d=((-1)*b+sqrt(f))/(2*a);
e=((-1)*b-sqrt(f))/(2*a);
printf("%f, %f",d,e);

/* Exit program. */
return 0;
}
/*--------------------------------------------------*/

 

[doodle]

1. To read doubles, use %lf in scanf().
2. You will need braces around the else body.

 

[piercas]

Dear user,

I can see that you have designed a program to calculate the real roots of a quadratic equation. However, you are getting an error message from the compiler stating that there is something wrong around the "if" statement. The error message specifically says "unrecognised types in comparison".

Upon reviewing your code, I noticed that you have declared the variables a, b, c, d, and e as double, but you are using the "%f" format specifier in the scanf() function, which is used for float data types. To fix this error, you can either change the data type of your variables to float or use the "%lf" format specifier in the scanf() function for double data types.

I hope this helps you fix the error and successfully calculate the real roots of a quadratic equation. Keep up the good work!