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  Arguments
 
    file_variable    Optional; text file (default is standard
                     file Input)
 
    variables        Optional; variable of any simple type except
                     Boolean
 
  Description
 
    The Readln procedure copies one or more values from a disk file or
    a device and places them into variables. The file must be a text
    file opened for input with Reset. After reading the file, Readln
    moves the current file position to the character following the
    next end-of-line marker or else to the end-of-file. A text file is
    read sequentially only.
 
    If no input file is specified, Readln reads from the standard text
    file Input. Standard input is from the keyboard unless redirected
    from a file by the DOS redirection operator, (<). Readln waits for
    all arguments to be entered when reading from the keyboard. Each
    input ends after a delimiting character for that type is entered.
    All input ends when ENTER is pressed. Keyboard input is echoed on
    the screen.
 
    Input redirection is disabled when the Crt unit is used. Use the
    Assign procedure with a null string to reenable DOS redirection
    when using Crt.
 
    If Readln is called with no arguments, it moves the current file
    position to the character following the next end-of-line or else to
    the end-of-file.
 
    Readln reads input according to the type of variable:
 
      1. Character input is read without use of delimiters.
 
         When Readln is called with a character variable and the
         current position is at end-of-line, it reads a carriage
         return (ASCII 13). It then moves the current position to the
         character following the carriage return.
 
         When Readln is called with a char variable and the current
         position is at end-of-file, it reads a CTRL+Z (ASCII 26).
         Subsequent calls to Read get CTRL+Z.
 
      2. Number input is delimited by blanks, tabs, or end-of-line
         markers. Read skips delimiters preceding an integer or real,
         and stops reading the number input when a delimiter occurs.
 
         For text files, Readln gets a 0 if end-of-file is true, or
         if it becomes true after skipping delimiters.
 
         If the input does not match the format of the variable
         receiving the value, an I/O error occurs.
 
      3. String input is delimited by an end-of-line or end-of-file,
         and the string that is read does not include the delimiter.
         Readln moves the current position to the character following
         the delimiter. Readln checks the length of the string variable
         and truncates the input if necessary.
 
    Readln treats CTRL+Z as an end-of-file. However, if the Crt
    unit is used, the effect of reading a CTRL+Z changes. CheckEOF is
    a Boolean variable defined in the Crt unit. When CheckEOF is False
    (default), an input of CTRL+Z is treated as any other input. When
    set to True, an input of CTRL+Z causes the end of input.
 
    If Readln is called with a file opened with the Append or Rewrite,
    procedures, an I/O error occurs.
 
    If file_variable is not associated with a file or if the file is
    not open when Readln is called, an I/O error occurs.
 
    To prevent a program from halting with a run-time error when an
    I/O error occurs, turn off I/O checking with {$I-} and check the
    return value of the IOResult function.