/* Pro69.c */
/* How to read any filename?  The simplest format by DOS command line. */

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

char inline[100];

main(int argc, char *argv[])
{
	FILE *fp;
	if (argc!=2){
	     printf("Usage: pro69.exe infile.txt > outfile.txt\n");
        }
	else
	     fp=fopen(argv[1], "r");

             /* Explanation of if()-else loop above.                              */
             /* argc counts arguments in the DOS command line from left.          */
	     /* Right side of redirection is not counted.  Thus this is argc=2,   */
             /* since (1) pro69.exe;  (2) infile.txt.   "!=" means Not Equal.     */
             /* Now, argv[0] is pro69.exe, argv[1] is infile.txt.   Else is       */
             /* opening "infile.txt".   If(argc!=2) is a cautious remark.         */


	while(fgets(inline, 100, fp)!=NULL){      /* Read infile.txt one line each time */
             printf("%s", inline);                /* Echo print out one line each time  */
	}
	fclose(fp);
	return 0;
}