/* file_I_O.c demonstrates file I/O
*  BJ Furman 15OCT2012 */ 

#include <stdio.h> 
#include <math.h> 
int main(void) 
{ 
	int i, j, k, num_elem; 
	double x[20], y[20], z[20]; 
	FILE *infile, *outfile; 

/* Open the file we want to read from. Simply putting the filename.type
*  between double quotes assumes that the file to open resides in the
*  SAME directory where this program resides. If the file you want to read 
*  from resides somewhere else, you'll need to put the full file path between
*  the double quotes. An example of this is given below for the output file.
*/
    
	infile = fopen ("C6_3_in.txt","r");
    //infile = fopen ("C:/Users/Buff/Documents/SJSU/Course related/ME 30/Lecture/C6_3_in.txt", "r");
    //infile = fopen ("C:\\Users\\Buff\\Documents\\SJSU\\Course related\\ME 30\\Lecture\\C6_3_in.txt", "r");
    
/* Check that file exists and is opened properly */  
    
    if(infile == NULL)
    {
        printf("Error: can't open file to read\n");
        return (1);
    }
    else
        printf("File C6_3_in.txt opened successfully to read\n");
    
/* Open the file that we want to write to. Putting "filename.type"
*  means that the file will be created in the SAME directory
*  where this program resides. If you want to put the file in a different
*  location, give the complete file path between the double quotes, which
*  you can find using Windows Explorer (Navigate to the directory you want, and
*  left-click in the URL bar at the top of the window.)
*  For example, the path to my Desktop is, C:\Users\Buff\Desktop
*  The backslashes will need to be 'escaped' themselves, so that they are not
*  confused with escape sequences or use a forward slash /. So the tweaked path is:
*  "C:\\Users\\Buff\\Desktop\\C6_3_out.txt" or "C:/Users/Buff/Desktop/C6_3_out.txt"
*/

	outfile = fopen ("C:\\Users\\Buff\\Desktop\\C6_3_out.txt","w"); 
    
/* Check that file exists and is opened properly */  

    if(outfile == NULL)
    {
        printf("Error: can't open file to write\n");

        return 1;
    }
    else
        printf("C6_3_out.txt opened successfully to write\n");

/* Read the first row. k captures the number values read in by fscanf() */    
	k = fscanf(infile,"%lf %lf",&x[0],&y[0]); 
    
/* Print the number of values read in by fscanf() */    
	fprintf (outfile, "k = %d\n",k); 

/* Print the value of EOF just so you can see what it is */        
	fprintf (outfile,"Value of EOF = %d\n", EOF); 
	 
	i = 1; // row counter variable

/* Get the rest of the values in the input file and print them out */    
	while ( fscanf(infile,"%lf %lf",&x[i],&y[i])   !=   EOF) 
    {
         printf("x[%d] == %lf y[%d] == %lf\n", i,x[i],i,y[i]);
       i++; 
    }
    
	num_elem = i; 
 
	fprintf(outfile,"   x[i]    y[i]    z[i]\n");
    
 /* Do some math on the values */
	for (j=0;j<num_elem;j++) 
		{ 
		z[j]=sqrt(x[j]*x[j]+y[j]*y[j]); 
            
/* print the results to a file */
		fprintf(outfile,"%7.1f %7.1f %7.1f\n",x[j],y[j],z[j]); 
		} 

/* Close the input and output files */   
    if(fclose(infile) == EOF)
        {
            printf("Error closing file\n");
            return 1;
        }
    else
        printf("C6_3_in.txt closed successfully\n");

    if(fclose(outfile) == EOF)
        {
            printf("Error closing file\n");
            return 1;
        }
    else
        printf("C6_3_out.txt closed successfully\n");
    
    return 0;
}