Help with this quadratic

Hello all,
I hope I am not bombarding you with my problem but I need to know what was wrong with the code below:

Code:

---

/* program to calculate the root of a quadratic equation*/
#include <stdio.h>
#include <math.h>
main()
{
  float a, b, c, d, r=0.0, x1, x2;
  printf ("\nEnter value for a\n");
  scanf ("%f", &a);
  printf ("\nEnter value for b\n");
  scanf ("%f", &b);
  printf ("\nEnter value for c\n");
  scanf ("%f", &c);
  d=sqrt((b*b)-4*a*c);
  if (d>r)
    x1=(-b+d)/(2*a);
    x2=(-b-d)/(2*a);
    printf("\nThe real roots are %f, %f\n", x1, x2);
  else if (d<r){
    printf ("\nThere are no real root because the equation turns to infinity\n");
    };
  else
    x1=(-b/2*a);
    x2=(-b/2*a);
    printf("\nThe real roots are %f, %f\n", x1, x2);
}

---

Below is the error:
c:\program files\miracle c\quadrati.c: line 18: Parse Error, expecting `'}''
'else if (d<r){ printf ("\nThere are no real root because the equation turns to infinity\n")'
aborting compile

Please help out.

Like it says, missing some brackets in your code:

Code:

---

  if (d>r) {
    x1=(-b+d)/(2*a);
    x2=(-b-d)/(2*a);
    printf("\nThe real roots are %f, %f\n", x1, x2);
    }
  else if (d<r){
    printf ("\nThere are no real root because the equation turns to infinity\n");
    }
  else {
    x1=(-b/2*a);
    x2=(-b/2*a);
    printf("\nThe real roots are %f, %f\n", x1, x2);
    }

---

[edit]Yeah, like Happy said, you should get rid of the semicolon as well... didn't catch that one before. ;)[/edit]

Your if-else statements should be in blocks like this :

Code:

---

if(condition)
{
        // do stuff
}
else
{
        // do other stuff
}

---

That's one thing. And the other thing is that :

Code:

---

else if (d<r){
    printf ("\nThere are no real root because the equation turns to infinity\n");
    };

---

You probably don't want that semi-colon there.

Further, you should get rid of Miracle C. It's as old as the dickens, there are better free compilers and IDE's out there.

Quote:

---

Further, you should get rid of Miracle C. It's as old as the dickens, there are better free compilers and IDE's out there.

---

I use Borland C 5.5 and got the same error as well.

Code:

---

/* program to calculate the root of a quadratic equation*/
#include <stdio.h>
#include <math.h>
main()
{
  float a, b, c, d, r=0.0, x1, x2;
  printf ("\nEnter value for a\n");
  scanf ("%f", &a);
  printf ("\nEnter value for b\n");
  scanf ("%f", &b);
  printf ("\nEnter value for c\n");
  scanf ("%f", &c);
  d=sqrt((b*b)-4*a*c);
  if (d>r){
    x1=(-b+d)/(2*a);
    x2=(-b-d)/(2*a);
    printf("\nThe real roots are %f, %f\n", x1, x2);
} 
else if (d<r){
    printf ("\nThere are no real root because the equation turns to infinity\n");
    }
  else {
    x1=(-b/2*a);
    x2=(-b/2*a);
    printf("\nThe real roots are %f, %f\n", x1, x2);
}

---

//Try that.

You need to check the sign of the discriminant before attempting to get the square root of it, as you may be trying to take the sqrt of a negative value. Eg.

Code:

---

d = b * b - 4 * a * c;
if(!d) printf("one real root: %f", -b / (2 * a));
if(d > 0)
{
        d = sqrt(d);
       
        printf("two real roots: %f, %f", (-b + d) / (2 * a), (-b - d) / (2 * a));
}
else printf("no real roots");

---

Quote:

---

Originally Posted by Happy_Reaper

Your if-else statements should be in blocks like this :

Code:

---

if(condition)
{
        // do stuff
}
else
{
        // do other stuff
}

---

That's one thing. And the other thing is that :

Code:

---

else if (d<r){
    printf ("\nThere are no real root because the equation turns to infinity\n");
    };

---

You probably don't want that semi-colon there.

Further, you should get rid of Miracle C. It's as old as the dickens, there are better free compilers and IDE's out there.

---

Honestly, i dont know what I could have done without the able and intelligent people in this forum, I did it and it works great. Thanks so much.

Quote:

---

Originally Posted by abs.emailverify

I use Borland C 5.5 and got the same error as well.

---

I never said the compiler was the problem, just that you should not use Miracle C (as it could potentially cause you problems).

and dont forget to include return in your main function. Main should always return 0. Include this at the end

Code:

---

return 0;

---

ssharish2005

> and dont forget to include return in your main function. Main should always return 0. Include this at the end

Supposed that main returns an integer value I guess ... what does just "main() {" return ? (?.?)

Quote:

---

Supposed that main returns an integer value I guess ... what does just "main() {" return ? (?.?)

---

Main should always return an int, and as such should be declared as int main().

> Main should always return an int, and as such should be declared as int main().

Hehe, I know, just wondering about this case.

Even in that case, I think most compilers default to int when a function's return value isn't specified. So main still returns an int. But you're going into compiler specific land...Not a good place to be.

Quote:

---

Originally Posted by TriKri

> and dont forget to include return in your main function. Main should always return 0. Include this at the end

Supposed that main returns an integer value I guess ... what does just "main() {" return ? (?.?)

---

it is by default int main(). You specify it or not it is int.

ssharish2005

> it is by default int main(). You specify it or not it is int.

Ok, thanks for the info. Though I'm not planing to ever use just "main() {". ;)