CODEWITHSUNDEEP
c
Scott
Scott

Reputation: 1

C Functions not returning

I am writing a program for class that has to use functions and I am not getting any syntax errors and have tried multiple times to change things with no success. The function is not saving into the .out file correctly.

Here is the code:

/* LAB13, functions                                       */
/* Given the number of sides of an n-side regular polygon */
/* and the radius of the circle, find the perimeter and   */
/* area of the polygon                                    */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define IN_FILE "lab13.dat"
#define OUT_FILE "lab13.out"

/* function prototypes */
double get_perimeter(double n, double radius);
double get_area(double n, double radius);

int main(void)
{
        double n;               /* number of sides          */
        double radius;          /* radius of the circle     */
        double area;            /* area of the polygon      */
        double perimeter;       /* perimeter of the polygon */

    FILE * data_in;     /* input file pointer  */
    FILE * data_out;    /* output file pointer */

    /* Open the two required files */
    data_in = fopen(IN_FILE, "r");
    if (data_in == NULL)
    {
        printf("Error on fopen file %s \n", IN_FILE);
        exit(EXIT_FAILURE);
    }

    data_out = fopen(OUT_FILE, "w");
    if (data_out == NULL)
    {
        printf("Error on fopen file %s \n", OUT_FILE);
        exit(EXIT_FAILURE);
    }
    /* Print headers */
    fprintf(data_out, "\nScott _________. Lab13. \n\n");
    fprintf(data_out, " Number Of Sides     Radius    Perimeter      Area    \n");
    fprintf(data_out, "   of Polygon      of Circle   of Polygon   of Circle \n");
    fprintf(data_out, "----------------   ---------   ----------   --------- \n");
    while ((fscanf(data_in, "%lf%lf", &n, &radius))== 2)
        {
           perimeter = get_perimeter(n, radius);
           area      = get_area(n, radius);
           fprintf(data_out,"%8i  %17.3f  %11.3f  %10.3f\n",
               n, radius, perimeter, area);
        }
    printf("\n");
    fclose(data_in);
    fclose(data_out);
    return EXIT_SUCCESS;
}

/*-----------------------------------------------------------*/
double get_perimeter(double n, double radius)
{
  double perimeter;

  perimeter = 2 * n * radius * (sin(M_PI/n));
  return perimeter;
}

/*-----------------------------------------------------------*/
double get_area(double n, double radius)
{
  double area;

  area = 0.5 * n * (radius*radius) * (sin(2*M_PI)/n);
  return area;
}

/*-----------------------------------------------------------*/

The lab13.dat file that it is grabbing from is:

3.0 16.5
5.0 9.1
7.0 11.5
The output from running the program

Upvotes: 0

Views: 99

Answers (2)

Chris Nevers
Chris Nevers

Reputation: 74

You're problem is in the fprintf.

fprintf(data_out,"%8i  %17.3f  %11.3f  %10.3f\n", n, radius, perimeter, area);

i is not the format specifier you want, use f. Probably a typo

Upvotes: 1

hobbs
hobbs

Reputation: 239732

You're printing n, which is a double, using the format %8i, which expects an int. If you want to print a double but suppress any possible non-integer part, use a precision of 0, as in %8.0f.

Upvotes: 1

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