/*  Replaces each newline by two newlines */
#include <stdio.h>
#include <stdlib.h>

void double_space(FILE *, FILE *);
void prn_info(char *);

main(int argc, char **argv)
{
  FILE *ifp, *ofp;

  if (argc != 3) {
	prn_info(argv[0]);
	exit(1);
  }
  ifp = fopen(argv[1], "r"); /* open for reading */
  ofp = fopen(argv[2], "w"); /* open for writing */
  double_space(ifp, ofp);
  fclose(ifp);
  fclose(ofp);
}

void double_space(FILE *ifp, FILE *ofp)
{
  int c;

  while ((c = getc(ifp)) != EOF) {
	putc(c, ofp);
	if (c == '\n')
	  putc('\n', ofp); /* found a new line - duplicate it */
  }
}

void prn_info(char *prog_name)
{
  printf("\n%s%s%s\n\n%s%s\n\n",
	"Usage: ", prog_name, " infile outfile",
	"The contents of infile will be double-spaced ",
	" and written to outfile.");
}