/*******
 * readwrite.c
 *
 * an example of reading (and writing) lines of text.
 *
 *******/

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

#define MAX_CHARS_PER_LINE 256
char input_buffer[MAX_CHARS_PER_LINE + 1];  // extra char for null terminator

char* readline(FILE* fileptr){
  // return string from reading next line of file or NULL if no more lines.
  char* result = NULL;
  int n_bytes;
  if (fgets(input_buffer, MAX_CHARS_PER_LINE, fileptr) != NULL){
    // copy string from input_buffer to new block of memory
    n_bytes = (1 + strlen(input_buffer)) * sizeof(char);
    result = malloc(n_bytes);         // allocate memory for new string
    strcpy(result, input_buffer);     // ... and copy it from input_buffer
  }
  return result;
}

FILE* openfile(char* filename){
  // return open file pointer
  FILE* fileptr = fopen(filename, "r");  // open for reading
  if (fileptr == NULL){                  // ... or exit with an error.
    printf("OOPS - error opening file '%s' \n", filename);
    exit(-1); // signal that an error happened.
  }
  return fileptr;
}

int main(){
  int n = 0;
  char* text = NULL;
  char filename[] = "hound.txt";
  FILE* fileptr = openfile(filename);
  printf("Reading '%s' ... \n", filename);
  while (1){
    text = readline(fileptr);
    if (!text){
      printf("... done. Read %d lines of text.\n", n);
      return 0;
    }
    n += 1;
    if (n < 10){
      // print the first few lines.
      printf(" line %3d : %s", n, text);   
    }
  }
}