Error: invalid operand to binary ^ (have 'int' and 'double')

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I am trying to write a programm which calculates the x1 and x2 of a quadratic equation.

What I have tried:

C++

#include <stdio.h>
#include <stdlib.h>

int main()
{
printf("ax^2+bx+c\n\n");
    int a, b, c;
    printf("enter integer a\n");
    scanf("%d", &a);
    printf("enter integer b\n");
    scanf("%d", &b);
    printf("enter integer c\n");
    scanf("%d", &c);

printf("x1=%d, x2=%d",(-b+(b*b-4*a*c)^0.5)/2*a, (-b-(b*b-4*a*c)^0.5)/2*a);




    return 0;
}

Posted 12-Oct-20 21:28pm

Member 14955513

Updated 12-Oct-20 22:50pm

CPallini

v2

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Rick York · Accepted Answer · 2020-10-12T21:39:00

Solution 1

The '^' operator in the C language is the binary exclusive or. It is NOT exponentiation.

Posted 12-Oct-20 21:39pm

Rick York

Comments

CPallini 13-Oct-20 4:08am

5.

Maciej Los 13-Oct-20 4:30am

5ed!

Richard MacCutchan · Accepted Answer · 2020-10-12T22:00:00

Solution 2

See pow, powf, powl | Microsoft Docs[^]

Posted 12-Oct-20 22:00pm

Richard MacCutchan

Comments

CPallini 13-Oct-20 4:08am

5.

Richard MacCutchan 13-Oct-20 4:20am

:thumbsup:

Maciej Los 13-Oct-20 4:30am

5ed!

Shao Voon Wong · Accepted Answer · 2020-10-12T22:23:00

Solution 3

Just use the sqrt function to calculate the square root.

Posted 12-Oct-20 22:23pm

Shao Voon Wong

Comments

CPallini 13-Oct-20 4:51am

5. Indeed.

Shao Voon Wong 13-Oct-20 5:49am

Thanks!

CPallini · Accepted Answer · 2020-10-12T22:51:00

To elaborate Rick and Richard solution, try

C

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

int main()
{
    printf("ax^2+bx+c\n\n");
    int a, b, c;
    printf("enter integer a\n");
    scanf("%d", &a);
    printf("enter integer b\n");
    scanf("%d", &b);
    printf("enter integer c\n");
    scanf("%d", &c);
    double d = b * b - 4 * a * c;
    if ( b < 0)
    {
      //TODO: show here the complex solutions 

    }
    else
    {
      d = sqrt(d);
      double x1, x2;
      x1 = (- b + d)/2/a;
      x2 = (- b - d)/2/a;
      printf("x1=%g, x2=%g\n", x1, x2);
    }
    return 0;
}

Please note:

You have to include the <math.h> header (and possibly link with the math library)
You don't actually need the pow function, the sqrt function is just enough
In order to divide something by 2a, you must write either
```
something/2/a
```
or
```
something/(2*a)
```
(writing,as you did, something/2*a is plain wrong).