lab10exF.c

/* lab10exF.c: solution to an ENCM 339 Fall 2005 exercise */

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

#define MAX_LINE_LENGTH 80 /* Does not include '\n' or '\0'. */
#define LINE_ARRAY_SIZE (MAX_LINE_LENGTH + 2)

void die(const char *msg);
/* REQUIRES: msg points to beginning of a string.
 * PROMISES: string is output to stderr, then program is terminated 
 *   with exit(1).
 */

int main(int argc, char **argv)
{
  FILE *fp;
  char line[LINE_ARRAY_SIZE];
  int line_number = 0;

  if (argc != 3)
    die("Number of arguments after program name must be two.\n");
  fp = fopen(argv[2], "r");
  if (fp == NULL)
    die("Could not open input file.\n");

  while(fgets(line, LINE_ARRAY_SIZE, fp) != NULL) {
    line_number++;
    if (strstr(line, argv[1]) != NULL)
      printf("%d:%s", line_number, line);
  }

  fclose(fp);
  return 0;
}

void die(const char *msg)
{
  fputs(msg, stderr);
  exit(1);
}