Question

KKKL1164 4. The C program presented below has some syntax and logic errors. Analyse it and highlight the errors, explaining how the errors can be corrected. This program attempts to solve a quadratic equation. #include <stdio.h> #include <math.h> int Main() const int a, b, Ci double doro, disc printf ("Lets find the root (s) of a printf ("ax 2 bx c. \n"); printf ("Please enter the coefficient a: scanf ("d", &c); printf ("Please enter the coefficient b: "); scanf ("8d", &b); printf ("Please enter the coefficient c: scanf ("%d", &a); printf ("The equation is %dx 2 Sdx 8d 0\n", quadratic equation ") ") ; "); a, b, c); c) i (4.9 a (b b) disc -- -b/(2.0 a) doro primtf ("The discriminant is =8.0f\n", disc); if (disc > 0); ( printf ("The equation has two real roots:\n"); printf ("R1 printf ("R2 =.2f\n", -b+sqrt (disc) ) / (2.0 a)) 8.2f\n", (+b-sqrt (disc))/(2.0 a)); else if (disc < 0) printf ("The equation has two complex roots: \n"); printf ("R1 printf ("R2 .1f .1fi\n", doro, sqrt(-disc)/ (2 a)); .1fi\n", doro, sqrt (-disc) / (2*a)) .1f else / disc printf ("The equation has a single root .1f\n", doro); return 0; (15 marks)

help

Answer 1

Code with errors:

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

int main()
{
   const int a, b, c;
   double doro, disc; // instead of double we may user float as all the format specifiers in code are float type, but if you use double its fine too. 
   
   printf("Lets find the root(s) of a quadratic equation ");
   printf("ax^2 + bx + c.\n");
   printf("Please enter the coefficient a: ");
   scanf("%d", &c); // This is a logical error as we are asking user for value of a and storing the input in variable c
   printf("Please enter the coefficient b: ");
   scanf("%d", &b);
   printf("Please enter the coefficient c: ");
   scanf("%d", &a); // This is a logical error as we are asking user for value of c and storing the input in variable a
   printf("The equation is %dx^2 + %dx + %d = 0\n", a, b, c);
   
   disc = (b * b) - (4.9 * a * c); // formula for discriminant is wrong
   doro = -b / (2.0 * a);
   printf("The discriminant is = %.0f\n", disc); // %.0f will display the value without decimal
   
   if (disc > 0); // if is not terminated with ;, i.e no ; needed after if (condition) {
      printf("The equation has two real roots:\n");
      printf("R1 = %.2f\n", (-b + sqrt(disc)) / (2.0 * a));
      printf("R1 = %.2f\n", (+b - sqrt(disc)) / (2.0 * a)); // formula for root is incorrect
   }
   else if (disc < 0) {
      printf("The equation has two complex roots:\n");
      printf("R1 = %.1f + %.1fi\n", doro, sqrt(-disc) / (2 * a));
      printf("R1 = %.1f - %.1fi\n", doro, sqrt(-disc) / (2 * a));
   }
   // the {} are not closed for else statement
   else { // disc = 0
      printf("The equation has a single root %.1f\n", doro);
   
   return 0;
}

correct code:

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

int main()
{
   const int a, b, c;
   float doro, disc;

   printf("Lets find the root(s) of a quadratic equation ");
   printf("ax^2 + bx + c.\n");
   printf("Please enter the coefficient a: ");
   scanf("%d", &a);
   printf("Please enter the coefficient b: ");
   scanf("%d", &b);
   printf("Please enter the coefficient c: ");
   scanf("%d", &c);
   printf("The equation is %dx^2 + %dx + %d = 0\n", a, b, c);

   disc = (b * b) - (4.0 * a * c);
   doro = -b / (2.0 * a);
   printf("The discriminant is = %.1f\n", disc);

   if (disc > 0) {
      printf("The equation has two real roots:\n");
      printf("R1 = %.2f\n", (-b + sqrt(disc)) / (2.0 * a));
      printf("R1 = %.2f\n", (-b - sqrt(disc)) / (2.0 * a));
   }
   else if (disc < 0) {
      printf("The equation has two complex roots:\n");
      printf("R1 = %.1f + %.1fi\n", doro, sqrt(-disc) / (2.0 * a));
      printf("R1 = %.1f - %.1fi\n", doro, sqrt(-disc) / (2.0 * a));
   }
   else { // disc = 0
      printf("The equation has a single root %.1f\n", doro);
   }

   return 0;
}


o/p:

Lets find the root(s) of a Please enter the coefficient a: 1 Please enter the coefficient b: 2 Please enter the coefficient c: 1 The equation is 1x^2 + 2x + 1 = e The discriminant is = 0.0 The equation has quadratic equation ax^2 +bx + c. single root -1.0 a Process exited after 4.043 seconds with return value e Press any key to continue

Lets find the root(s) of a Please enter the coefficient a: 1 Please enter the coefficient b: 0 Please enter the coefficient c: -4 The equation is 1x^2 + 0x + -4 The discriminant is = 16.0 The equation has two real roots: R1 R1 quadratic equation ax^2 + bx + c. = 0 - 2.00 -2.00 Process exited after 3.932 seconds with return value 0 Press any key to continue

Lets find the root (s) of a quadratic equation ax 2 + bx + c. Please enter the coefficient a: 5 Please enter the coefficient b: 8 Please enter the coefficient c: 5 The equation is 5x^2 + 8x + 5 = e The discriminant is -36.0 = The equation has two complex roots: -0.8 + 0.6i R1 = 0.6i R1 -0.8 = Process exited after 7.539 seconds with return value 0 Press any key to continue

For help please comment.

Thank you