Thread: Help finding bugs

Hello, I'm completely new to programming and I'm really struggling to find the bugs in the following pieces of code. Please help me out.

Code 1:

Code:

/* BUG ZONE!!!Example: integer arithmetic */

#include <stdio.h>

main()
{
  int r1 = 22000;
  int r2 = 10000;
  int r3 = 15000;
  int r;
  
  puts("Three resistors in parallel");
  printf("%i || %i || %i\n\n", r1, r2, r3);
  
  puts("Method 1: r = (r1 * r2 * r3)/(r1*r2 + r2*r3 + r3*r1)\n");
  r = (r1 * r2 * r3)/(r1*r2 + r2*r3 + r3*r1);  /* BUG */
  printf("Total resistance = %i\n\n", r);
  
  puts("Method 2: r = 1/(1/r1 + 1/r2 + 1/r3)\n");
  r = 1/(1/r1 + 1/r2 + 1/r3);  /* BUG */
  printf("Total resistance = %i\n", r);
}

Code 2:

Code:

/* BUG ZONE!!!
Example: integer arithmetic */

#include <stdio.h>

main()
{
  int StudentsInClass = 116;
  int MaxGroupSize = 5;
  int NumberOfGroups;
  int passes;
  int GirlsWithBrownEyes;
  
  NumberOfGroups = StudentsInClass/MaxGroupSize; /* BUG */
  
  printf("%i students at %i max. per group means %i groups\n\n", 
    StudentsInClass, MaxGroupSize, NumberOfGroups);
    
  /* Three-quarters of the class pass the exam: */
  
  passes = 3/4 * StudentsInClass;  /* BUG */
  printf("%i students passed the exam!\n\n", passes);
  
  /* Half the students are female, and 
  half of these have brown eyes */
  
  GirlsWithBrownEyes = StudentsInClass / 2*2;  /* BUG */
  
  printf("There are %i brown-eyed girls in the class\n",
    GirlsWithBrownEyes);
}

Thanks for replying. So do I just need to replace the ints with floats?

Have you tried doing that and seeing the results? It takes literally seconds to compile and run a program of this size, so doing some experimentation would help you test your ideas.

Code:

3/4

This is an example of what Salem was talking about. 3 and 4 are both integers, and integer division yields an integer result (i.e. any fractional part is discarded).

Try this instead:

Code:

3.0 / 4.0

This won't solve all your problems, but should be a good nudge in the right direction.