So I\'m pretty new to C programming and having a lot of trouble getting this to

Question

So I'm pretty new to C programming and having a lot of trouble getting this to work. I need to read in a file that has data on it (couple lines in sets of 2's) and I need to use that data to print out the perimeter and area of a polygon within a circle. My professor didn't really do a good job of setting us up so I'm having trouble debugging my work. This is what I have wrote so far.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define INPUT_FILE "lab3.dat"
#define ANSWER_FILE "lab3.txt"

int main(void)
{
   double nsides;
   double radius;
   double perimeter;
   double area;
   FILE* my_data;
   FILE* out_file;
   my_data = fopen(INPUT_FILE, "r");
   if(my_data == NULL)
   {
  
       printf("Error on opening the data file ");
   }
   out_file = fopen(ANSWER_FILE,"w")
   if(out_file == NULL)
   {   
       printf("Error on opening the output file ");
   }
   perimeter = 2*nsides*radius*sin(M_PI/nsides);
   area = 0.5*nsides*(radius*radius)*sin((2*M_PI)/nsides);

   fprintf(ANSWER_FILE, " Nima Sarrafzadeh. Lab 3. ");
   fprintf(ANSWER_FILE, "            Number      Perimeter      Area Of ");
   fprintf(ANSWER_FILE, " Radius    Of Sides    Of Polygon      Polygon ");
   fprintf(ANSWER_FILE, "--------   --------   ------------   ----------- ");
   while((fscanf(my_data, "%d%f", &radius, &nsides))==2)
   {
       fprintf(ANSWER_FILE, ("%d", radius), "   ", ("%d", nsides), "   ", ("%d", perimeter), "      ", ("%d", area);
   }
   fclose(INPUT_FILE);
   fclose(ANSWER_FILE);
}

Explanation / Answer

Hi, I have fixed all the issue.

Please find my code.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define INPUT_FILE "lab3.dat"
#define ANSWER_FILE "lab3.txt"

int main(void)
{
int nsides;
double radius;
double perimeter;
double area;

FILE* my_data;
FILE* out_file;

my_data = fopen(INPUT_FILE, "r");
if(my_data == NULL)
{
  
printf("Error on opening the data file ");
exit(0);
}

out_file = fopen(ANSWER_FILE,"w");
if(out_file == NULL)
{   
printf("Error on opening the output file ");
exit(0);
}

// now reading number of sides and radius value from file
if((fscanf(my_data, "%d%lf", &nsides, &radius))!=2)
{
printf("Data is not available in file ");
exit(0);
}

perimeter = 2*nsides*radius*sin(M_PI/nsides);
area = 0.5*nsides*(radius*radius)*sin((2*M_PI)/nsides);

fprintf(out_file, " Nima Sarrafzadeh. Lab 3. ");
fprintf(out_file, " Number Perimeter Area Of ");
fprintf(out_file, " Radius Of Sides Of Polygon Polygon ");
fprintf(out_file, "-------- -------- ------------ ----------- ");

fprintf(out_file, "%d %lf %lf %lf",nsides, radius, perimeter, area);
  

fclose(my_data);
fclose(out_file);
}

######## lab3.dat ########

5
4.5

######## output: lab3.txt ##############

Nima Sarrafzadeh. Lab 3.

Number Perimeter Area Of
Radius Of Sides Of Polygon Polygon
-------- -------- ------------ -----------
5 4.500000 26.450336 48.147236

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