/*
 * fileIO - read a list of file names as command-line arguments, 
 *          and print the first line of each file. 
 *          return status is the # of files that it fails to read
 * 
 * usage: ./fileIO [filename]....
 * 
 * CS50, Spring 2022
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>  // only need it if option 2 is used

int main(const int argc, const char* argv[])
{
  int status = 0;
  FILE *fp; 

  for (int i = 1; i < argc; i++) {
    if ((fp = fopen(argv[i], "r")) == NULL) {
      fprintf(stderr, "failed to open %s\n", argv[i]);
      status++; 
      continue; // move on to the next argument/file
    }
    // read a line
    printf("%s: ", argv[i]); 
    // option 1: read by characters
    char c; 
    while ((c = fgetc(fp)) != EOF) {
      putchar(c);
      if (c == '\n') {
        break; 
      }
    }

/* the following two options are less optimal as 
   they assume a maximal line length */

    // option 2: read by lines
    /*
    char line[100];   // buffer to store a line
    if (fgets(line, 100, fp) != NULL) {
      int len = strlen(line);
      if (line[len-1] == '\n') {
        line[len-1] = '\0';
      }
      printf("%s\n", line);
    }
    */

    // option 3: read by format
    /*
    char line[100];   // buffer to store a line
    if (fscanf(fp, "%[^\n]", line) == 1) {
      printf("%s\n", line);
    }
    */
  	
    // close file 
    fclose(fp);
  }

  return status;
}