/* 
 * names0.c - read in a list of names from stdin
 *   (two-dimensional array; each row is still a pointer)
 *
 * usage: names < infile
 * stdin: list of names, one per line
 * stdout: numbered list of names, one per line
 * 
 * David Kotz, April 2016, 2017
 */

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

/* function prototypes */
bool readline(char *buf, const int len);

/* main */
int main()
{
  const int maxNames = 100;  // maximum number of names
  const int maxLength = 50;  // maximum length of a name (minus 2)
  char names[maxNames][maxLength];
  int n = 0;		     // number of names read

  // read the list of names
  for (n = 0; n < maxNames && !feof(stdin); ) {
    if (readline(names[n], maxLength)) {
      n++; // only increment if no error
    }
  }

  printf("%d names\n", n);
  // print the list of names; note each name ends in newline.
  for (int i = 0; i < n; i++) {
    printf("%d: %s", i, names[i]);
  }
}

/* readline - Safely read a line of input into `buf`.
 *
 * Caller provides buffer `buf` with room for `len` characters.
 * We fill `buf` by reading characters from stdin,
 * guaranteeing we won't over-run the end of the buffer,
 * guaranteeing a newline-terminated, null-terminated string in the buffer;
 * returning true if success and false if EOF or any error.
 * If the user enters more than len-2 characters, that is considered an error.
 * If end-of-file is reached before newline, that is considered an error.
 * If an error occurs, buf may have been written but should be untrusted.
 */
bool readline(char *buf, const int len) 
{
  int pos = 0;		      // where in the buffer do we place next char?

  // fill the buffer from stdin until buf is full, until EOF, or until newline
  while ( !feof(stdin) && pos < len-1 ) {
    // read and store a character
    char c = getchar();
    buf[pos++] = c;

    if (c == '\n') {
      // end of line: terminate buf and return
      buf[pos++] = '\0';
      return true;
    }
  }
  // terminate buffer
  buf[pos++] = '\0';

  // error: file ended or buffer filled before newline discovered.

  // strip characters until end of file or newline is finally reached
  while ( !feof(stdin) && getchar() != '\n' ) {
    ; // discard the rest of characters on input line
  }

  return false;
}