Thread: help with simple debugging

Originally posted by Wexy
The code compiles fine, but when it is run, the menu will come up twice and it will say invalid keypressed even when nothing is pressed. When it does the computations it always gives the incorrect answer of 0.00..Thanks in advance for any help!

Code:

 start:
  printf("Compute what?:\n");
  printf("\t -> (R)adius\n");
  printf("\t -> (C)ircumerfece\n");
  printf("\t -> (S)urface Area\n");
  printf("\t -> (V)olume\n");
  printf("\t -> (Q)uit\n");
  printf("Your choice:  ");
  scanf("%c",&choice);
  printf("------------\n");

  switch(choice)
    {
    case 'r': case 'R':
      Radius();
      GetOption();
    case 'c': case 'C':
      Circumference();
      GetOption();
    case 's': case 'S':
      SurfaceArea();
      GetOption();
    case 'v': case 'V':
      Volume();
      GetOption();
    case 'q': case 'Q':
      exit(EXIT_SUCCESS);
    default:
      printf("Invalid key pressed, Try Again\n");
      goto start;  // NEVER REALLY A GOOD IDEA, ERROR!!
      }
}

For pne you used GOTO which is the cause for your double output menu. simply because the choices you make are invalid and it jumps back to start again. Figure out another way w/o using goto().
later,
cj

in your function getinput() where the scanf is make this modification

Code:

scanf("\n%c",&choice);

Okay your are always getting 0.00 that because you arnt passing daimeter to any of the functions..

Modify your program so that functions raduis() and so on... take a float varaible daimeter ....

i think it should work and yes please GOTO statements arnt ment for newbies .....only use them in huge programmes ..There is always a structured way to do it .....C is a procedural programming lang keep it that way ....

Code:

#include <stdio.h>
#include <stdlib.h>
#define pi 3.141592

void GetInput ( float *);
void GetOption (float );
void Radius (float );
void Circumference (float);
void SurfaceArea (float);
void Volume (float);


int main ()
{
 float diameter;

  GetInput(&diameter);
  GetOption(diameter);

  system("pause");
  return 0;
}

void GetInput (float *diameter)
{
  printf("\n\nEnter diameter in meters: ");
  scanf("%f",diameter);
  while ( *diameter <= 0.0 )
    {
         printf("\nMust be greater than 0.0. Try again\n");
         printf("\nEnter diameter in meters: ");
         scanf("%f",&diameter);
    }

}


void GetOption(float diameter)
{
  char choice;
 start:
  printf("Compute what?:\n");
  printf("\t -> (R)adius\n");
  printf("\t -> (C)ircumerfece\n");
  printf("\t -> (S)urface Area\n");
  printf("\t -> (V)olume\n");
  printf("\t -> (Q)uit\n");
  printf("Your choice:  ");
  scanf("\n%c",&choice);
  printf("------------\n");

  switch(choice)
    {
    case 'r': case 'R':
      Radius(diameter);
      GetOption(diameter);
    case 'c': case 'C':
      Circumference(diameter);
      GetOption(diameter);
    case 's': case 'S':
      SurfaceArea(diameter);
      GetOption(diameter);
    case 'v': case 'V':
      Volume(diameter);
      GetOption(diameter);
    case 'q': case 'Q':
      exit(EXIT_SUCCESS);
    default:
      printf("Invalid key pressed, Try Again\n");
      goto start;
      }
}

void Radius(float diameter)
{
  float ans;
  ans = ( diameter / 2 );
  printf("Radius is %f meters\n",ans);
}
void Circumference(float diameter)
{
  float ans;
  ans = 2 * pi * diameter ;
  printf("Circumference is %f meters",ans);
}
void SurfaceArea(float diameter)
{
  float ans,radius;
  radius = (diameter / 2);
  ans = pi * (radius * radius);
  printf("Surface Area is %f square meters",ans);
}
void Volume(float diameter)
{
  float ans,ans2;
  ans = pi  * (diameter / 2) * diameter;
  ans2 = ans * ans;
  printf("Volume is %f cubic meters",ans2);
}