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

int main(int argc, char* argv[])
{	FILE* f1;
	FILE* f2;
	char* progname;
	char* p;
	int c1,c2;
	char buf1[BUFSIZ];
	char buf2[BUFSIZ];
   int same;

	p = strrchr(argv[0], '\\');
	progname = p ? p+1 : argv[0]; /* name of this program, */
	p = strrchr(progname, '.'); /* with path and extension removed */
	if (p) *p = 0;

	if (argc != 3)
	{	printf( "Usage: %s file1 file2   compares file1 and file2\n", progname );
		printf( "       If the files are identical, file2 is erased.\n" );
		printf( "       If the files are different, file2 replaces file1.\n" );
		printf( "       If file1 does not exist, file2 is renamed to file1.\n" );
		exit(1);
	}

	if (access(argv[1], 0) != 0) /* file1 doesn't exist */
	{	rename(argv[2], argv[1]);
		printf("%s created.\n", argv[1]);
		return 0;
	}

	f1 = fopen(argv[1], "r");
	if (!f1)
	{	printf("%s: Can't open %s\n", progname, argv[1]);
		exit(1);
	}

	f2 = fopen( argv[2], "r" );
	if (!f2)
	{	printf("%s: Can't open %s\n", progname, argv[2]);
		exit(1);
	}
#if 0
	do
	{	c1 = fgetc(f1);
		c2 = fgetc(f2);
	} while( c1 == c2 && c1 != EOF );
#endif
	do
	{	c1 = fread(buf1, 1, BUFSIZ, f1);
		c2 = fread(buf2, 1, BUFSIZ, f2);
		same = c1 == c2 && memcmp(buf1, buf2, c1) == 0;
	} while (same && c1 == BUFSIZ);

	fclose( f1 );
	fclose( f2 );
#if 0
	if (c1 == c2) /* == EOF */
#endif
	if (same)
	{	remove(argv[2]);
		printf("No change.\n");
		return 1;
	}
	else
	{	remove(argv[1]);
		rename(argv[2], argv[1]);
		printf("%s updated.\n", argv[1]);
		return 0;
	}
}