String :: isEOF - Does string singnal end of file
When reading text files (TextFile::readLine()), the end of file is indicated by returning an end of file mark in the string, which may be checked calling this function. In case of file end, the function returns true and false otherwise (also for an empty string).
Return value: Success ( bool )
The value is true when the function was executed successfully. Otherwise the value is set to false.