#include <stdio.h>

int main ()
{
  // Some variables: an int, a double, a char and a string.
  int i = 1;
  double x = 2.5;
  char ch = 'a';
  char *str = "hello";

  // A char array to hold input lines.
  char inputLine [100];

  // Declare a file pointer. Note the capitalization.
  FILE *dataFile;

  // Open the file.
  dataFile = fopen ("data.txt", "w");

  // Print the four variables.
  printf ("i = %d  x=%lf  ch=%c  str = %s\n", i, x, ch, str);
  fprintf (dataFile, "i = %d  x=%lf  ch=%c  str = %s\n", i, x, ch, str);  // Write to file.

  // Scanning in numbers:
  printf ("Enter an integer followed by a double: ");
  scanf ("%d %lf", &i, &x);
  printf ("i = %d   x = %lf\n", i, x);
  fprintf (dataFile, "i = %d   x = %lf\n", i, x);                         // Write to file.

  // Scanning in a string:
  printf ("Enter a string: ");
  scanf ("%s", inputLine);
  printf ("You entered: %s\n", inputLine);
  fprintf (dataFile, "You entered: %s\n", inputLine);                     // Write to file.

  // Close the file.
  fclose (dataFile);
}