Compiling errors...(30 lines of code)

Code:

#include <stdio.h>
#define MAX_ARRAY_SIZE 20
int get_corners(FILE* fp,double x_array[],double y_array[],MAX_ARRAY_SIZE);
  
 void output_corners(FILE* foutput,double x_array[],double y_array[],int *actual_size);
  
 double polygon_area(double x_array[],double y_array[],int*actual_size);
   
   int main(int argc,char*argv[])
  {
  int actual_size;
  double x_array[MAX_ARRAY_SIZE];
  double y_array[MAX_ARRAY_SIZE];
  int i=0;
  int j=0;
  
  FILE *fp;                                                                           //opens a file and reads it. Then calls get_corners function which then extracts data from it
   fp =fopen(argv[1],"r");
  get_corners(&fp,x_array,y_array,MAX_ARRAY_SIZE);
  
  FILE *foutput;                                                                   //opens a file and writes to it. Using output parameters
  foutput=fopen(argv[2],"w");
  output_corners(&foutput,x_array,y_array,&actual_size);
  
  polygon_area(x_array,y_array,&actual_size);                      //calculates polygon area
  return 0;
  }//main
  
  
  int get_corners(FILE *fp,double x_array[],double y_array[],MAX_ARRAY_SIZE)
  {
  FILE *fp;
  fp =fopen(argv[1],"r");
  while(fscanf(fp,"%lf%lf",&x_array[i],&y_array[j])!=EOF)
  {
  i++;
  j++;
  }
  return *actual_size=j;
  
  }
  
  void output_corners(FILE*foutput,double x_array[],double y_array[],int *actual_size)
  {
  
  
  }
  double polygon_area(double x_array[],double y_array[],int *actual_size)
  {
  
  return 0;

gcc -Wall polygon.c
polygon.c:5:60: error: expected declaration specifiers or '...' before numeric constant

polygon.c: In function 'main':
polygon.c:19:1: warning: implicit declaration of function 'get_corners' [-Wimplicit-function-declaration]
polygon.c:23:1: warning: passing argument 1 of 'output_corners' from incompatible pointer type [enabled by default]
polygon.c:6:6: note: expected 'struct FILE *' but argument is of type 'struct FILE **'

polygon.c: At top level:
polygon.c:30:60: error: expected declaration specifiers or '...' before numeric constant

Can someone tell me why my macro MAX_ARRAY_SIZE is showing up as an error? (Line 5)

Also whats wrong with Lines 6,19,23?

Thanks so much guys

Code:

get_corners(&fp,x_array,y_array,MAX_ARRAY_SIZE);

should be

Code:

get_corners(fp,x_array,y_array,MAX_ARRAY_SIZE);

Thats one thing and look at this

Code:

int get_corners(FILE* fp,double x_array[],double y_array[],MAX_ARRAY_SIZE);

I dont think you mean to put MAX_ARRAY_SIZE in that spot.

Remember that MAX_ARRAY_SIZE is a constant, meaning you do not have to pass it in to your functions.