[Tutor] Escape codes and 'return statements'
Thu, 17 Aug 2000 11:37:16 +0100
> Hi this is Albert,
> I'm currently learning Python and I came across this
> things called "escape codes". I understand fairly most of
> them except for the escape codes ' \n ' and (linefeed???) and
> ' \r ' (carriage return).
I assume you are confused about the difference?
Back in the mists of computing time(up until the
late 1970's) computers had teletypes for input/output
Teletypes had rolls of paper on which the printing was
done and you could issue a linefeed to move the roll
up one line at a time. This was mechanically much more
efficient than moving up and moving the carriage back
each time so if you wanted 3 blank lines you issued 3
They also had carriage return to bring the printhead back
to the beginning of the line. Thus typically the user would
type(or the program would output) a carriage return followed
by one or more line feeds.
These two motions got encapsulated in ASCII by the control
chararacters ^J(linefeed) and ^M(carriage return/linefeed)
With the advent of VDUs the need for a separate linefeed
diminished and mostly we just use carriage return/linefeed
as a single 'newline' command.
Thus '\r' is a pure linefeed with no c/r and '\n' combines
I'm not sure if there is a character for c/r only (which
can be usefgul for controlling old printers which can only
use one color per line - multiple passes allows multiple
colors in a line, for example)
Does that help in any way?
Mostly you just need to use '\n'....
> Also, I kinda understand 'return' statements but I would
> like to know on how and when to use them properly.Thanks in advance.
Oooh thats a religious question. :-)
Simply put return causes an immediate return from the current
function. Purists like to see a single return statement per
function. Those of us brought up on C tend to use them rather