1
00:00:01,030 --> 00:00:02,470
- [Instructor] Next,
we're going to take a look

2
00:00:02,470 --> 00:00:06,600
at what are known as
raw strings in Python.

3
00:00:06,600 --> 00:00:09,550
Now you may recall that
the backslash character

4
00:00:09,550 --> 00:00:14,140
within a string normally
introduces an escape sequence.

5
00:00:14,140 --> 00:00:17,000
So for example, Backslash
+ n if it were to appear

6
00:00:17,000 --> 00:00:18,990
within a string would represent the

7
00:00:18,990 --> 00:00:21,200
new line escape sequence.

8
00:00:21,200 --> 00:00:25,030
Now, when you're going things
like creating file paths

9
00:00:25,030 --> 00:00:27,610
on the Microsoft Windows operating system,

10
00:00:27,610 --> 00:00:30,003
such as the example I just pasted in here,

11
00:00:30,003 --> 00:00:34,430
backslashes are used to
separate your folder names.

12
00:00:34,430 --> 00:00:36,400
So, if you're creating a string

13
00:00:36,400 --> 00:00:39,450
that represents a Windows
path you would need

14
00:00:39,450 --> 00:00:42,860
to use two backslashes in every location

15
00:00:42,860 --> 00:00:45,690
where a backslash is
required in a Windows path

16
00:00:45,690 --> 00:00:50,690
because by default the backslash
inside of a string is used

17
00:00:50,810 --> 00:00:52,570
to indicate an escape sequence.

18
00:00:52,570 --> 00:00:53,460
So, you'd actually have

19
00:00:53,460 --> 00:00:56,810
to use the backslash
characters escape sequence

20
00:00:56,810 --> 00:00:59,320
to properly encode that string

21
00:00:59,320 --> 00:01:02,700
and if I go ahead and display

22
00:01:02,700 --> 00:01:05,230
that you can see we get the same thing

23
00:01:05,230 --> 00:01:08,170
as we had entered in the
string up above here.

24
00:01:08,170 --> 00:01:11,250
Now, that can be really painful to do

25
00:01:11,250 --> 00:01:13,960
when you're dealing with
Windows paths a lot,

26
00:01:13,960 --> 00:01:17,540
or as we go into the
next sequence of videos

27
00:01:17,540 --> 00:01:20,510
and start to introduce
regular expressions.

28
00:01:20,510 --> 00:01:24,050
Backslashes are used
in regular expressions

29
00:01:24,050 --> 00:01:26,290
for pattern matching quite a lot.

30
00:01:26,290 --> 00:01:31,290
So, there's a concept in
Python called a raw string

31
00:01:31,350 --> 00:01:35,400
and with a raw string it
just assumes every character

32
00:01:35,400 --> 00:01:38,810
in the string is its literal value.

33
00:01:38,810 --> 00:01:42,370
So, this is the same file
path as a raw string,

34
00:01:42,370 --> 00:01:44,850
which is a string
starting with the letter r

35
00:01:44,850 --> 00:01:48,830
before its opening quote
and as you can see here I'm

36
00:01:48,830 --> 00:01:53,550
not using double backslashes
throughout this Windows path

37
00:01:53,550 --> 00:01:55,070
that I've created.

38
00:01:55,070 --> 00:02:00,070
However, when I evaluate
that same path you can see

39
00:02:00,960 --> 00:02:04,910
that it is still creating
the string properly

40
00:02:04,910 --> 00:02:06,970
with the two backslashes

41
00:02:06,970 --> 00:02:09,520
at each location underneath the hood.

42
00:02:09,520 --> 00:02:12,190
So, this is a convenience notation

43
00:02:12,190 --> 00:02:14,680
for anytime you're dealing with strings

44
00:02:14,680 --> 00:02:19,260
that can contain literal
backslash characters in particular

45
00:02:19,260 --> 00:02:22,934
and other escape character
sequences as well

46
00:02:22,934 --> 00:02:25,140
that you simply want to be treated

47
00:02:25,140 --> 00:02:28,513
as their individual character values.