Is EOF always negative?

Question

Is EOF always negative?

I\'m thinking of writing a function that reads the next word in the input and returns the line number the word was found in or

Answer 1

From the online draft n1256, 17.9.1.3:

EOF

which expands to an integer constant expression, with type int and a negative value, that is returned by several functions to indicate end-of-file, that is, no more input from a stream;

EOF is always negative, though it may not always be -1.

For issues like this, I prefer separating error conditions from data by returning an error code (SUCCESS, END_OF_FILE, READ_ERROR, etc.) as the function's return value, and then writing the data of interest to separate parameters, such as

int getNextWord (FILE *stream, char *buffer, size_t bufferSize, int *lineNumber)
{
  if (!fgets(buffer, bufferSize, stream))
  {
    if (feof(stream)) return END_OF_FILE; else return READ_ERROR;
  }
  else
  {
    // figure out the line number
    *lineNumber = ...;
  }
  return SUCCESS;
}