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/* Simple C typedefs and helper functions for strings and I/O
 * SI204, Spring 2017
 * Dr. Roche
 */

/* Make sure nothing bad happens if you #include this file twice */
#ifndef SI204_H
#define SI204_H

/* Standard header files */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Define a special type "cstring" which is just a char array
 * of a predetermined, fixed length.
 * XXX: If you change this, be sure to update CSTRINGSCAN below also. */
#define CSTRINGLEN (128)
typedef char cstring[CSTRINGLEN];

/* The scanf argument for a cstring.
 * Note the length is CSTRINGLEN-1 for the null character. */
#define CSTRINGSCAN "%127s"

/* Typedef for stream, which is the same as FILE* */
typedef FILE* stream;

/* Function prototypes defined here.
 * Note: they are declared "static" because the implementations are
 * below, not in a separately-compiled file.
 */
static char readchar(stream in);
static void readstring(cstring s, stream in);
static double readnum(stream in);
static void writenum(double x, stream out);

/* Function definitions below */

char readchar(stream in) {
  char c;

  /* when reading from stdin, make sure all pending stdout output
   * is written first */
  if (in == stdin) fflush(stdout);

  /* The fscanf is the most important part!
   * It returns the number of items successfully read. */
  if (fscanf(in, " %c", &c) != 1) {
    fprintf(stderr, "\nERROR in readchar. Maybe end-of-file?\n");
    abort();
  }

  return c;
}

void readstring(cstring s, stream in) {
  /* when reading from stdin, make sure all pending stdout output
   * is written first */
  if (in == stdin) fflush(stdout);

  /* The fscanf is the most important part!
   * It returns the number of items successfully read. */
  if (fscanf(in, CSTRINGSCAN, s) != 1) {
    fprintf(stderr, "\nERROR in readstring. Maybe end-of-file?\n");
    abort();
  } else if (strlen(s) >= CSTRINGLEN - 1) {
    fprintf(
        stderr,
        "\nERROR: Input string is too long (must be at most %d characters).\n",
        CSTRINGLEN - 2);
    abort();
  }
}

double readnum(stream in) {
  double x;

  /* when reading from stdin, make sure all pending stdout output
   * is written first */
  if (in == stdin) fflush(stdout);

  /* The fscanf is the most important part!
   * It returns the number of items successfully read. */
  if (fscanf(in, "%lf", &x) != 1) {
    if (feof(in)) fprintf(stderr, "\nERROR in readnum: EOF reached.\n");
    else fprintf(stderr, "\nERROR in readnum: Maybe ill-formatted number?\n");
    abort();
  }

  return x;
}

void writenum(double x, stream out) {
  /* The fprintf is the most important part!
   * It returns the number of characters actually printed. */
  if (fprintf(out, "%g", x) <= 0) {
    fprintf(stderr, "\nERROR on writenum. Maybe the stream is invalid?\n");
    abort();
  }
}

#endif /* ifdef SI204_H */