/* fileio-3.c

   demonstrates the following:

   - FILE, fopen, fwrite, fread, fclose
   - writing and reading binary files of primitives
   - formatted console I/O of values read from binary files
   - #define
   - ferror() - returns a value that is re-initialized by each call to fwrite or fread. non zero value indicates I/O error
   - feof() returns true or false if EOF has been encountered on the stream just read
   Expects a command line arg: name of binary output file to be created

   Writes ten ints followed by ten doubles to that file then reopens the file fo reading, and echoes values to console
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define NUM_INTS      10
#define NUM_DOUBLES   10

int main( int argc, char *argv[] )
{

	FILE *binaryFile;

	int     i;       /* loop counter as values are writen/read to/from file */
	int     iVal;    /* a sequence of these will be written to outfile */
	double  dVal;    /* folowed by a sequence of these  */

	if (argc < 2)
	{
		printf("usage: ./a.out <outputFilename> \n");
		exit(0);
	}

	/* OPEN FOR WRITE   */

	binaryFile = fopen( argv[1], "w" );
	if (binaryFile == NULL)
	{
		fprintf(stderr,"Can't open binary output file %s\n", argv[1] );
		exit(EXIT_FAILURE);
	}

	/* WRITE TEN INTS & TEN DOUBLES */

	for (i=0 ; i<10 ; ++i)
		if ( fwrite( &i, sizeof(i), 1, binaryFile ) != 1)
		{
			if ( ferror(binaryFile) )
				printf("I/O Err (fwrite)\n" );
			else
				printf("???\n" );
			exit(0);
		}

	for (dVal=0.0; dVal < 10.0 ; dVal += 1.0)
		if ( fwrite( &dVal, sizeof(dVal), 1, binaryFile ) != 1)
		{
			if ( ferror(binaryFile) )
				printf("I/O Err (fwrite)\n" );
			else
				printf("???\n" );
			exit(0);
		}

    fclose( binaryFile );

    /* RE-OPEN FOR READ BINARY. ECHO TO CONSOLE */

	binaryFile = fopen( argv[1], "r" );

	if (binaryFile == NULL)
	{
		printf("Can't open binary input file %s\n", argv[1] );
		exit(0);
	}

	/* READ/ECHO  TEN INTS & TEN DOUBLES */

	for ( i=0 ; i<10 ; ++i )
		if ( fread( &iVal, sizeof(iVal), 1, binaryFile) == 1 )
			printf("%d ",iVal );
		else
		{
			if ( ferror(binaryFile) )
				printf("I/O Err (fread)\n" );
			else if ( feof(binaryFile) )
				printf("Premature EOF (fread)\n" );
			else
				printf("???\n" );
			exit(0);
		}
	printf("\n");

	for ( i=0 ; i<10 ; ++i )
		if ( fread( &dVal, sizeof(dVal), 1, binaryFile) == 1 )
			printf("%f ",dVal );
		else
		{
			if ( ferror(binaryFile) )
				printf("I/O Err (fread)\n" );
			else if ( feof(binaryFile) )
				printf("Premature EOF (fread)\n" );
			else
				printf("???\n" );
			exit(0);
		}
	printf("\n");

    fclose( binaryFile );

	return EXIT_SUCCESS;

} /* END MAIN */