1
00:00:00,000 --> 00:00:00,360

2
00:00:00,360 --> 00:00:02,390
>> SPEAKER 1: It turns out this program,
short though it is,

3
00:00:02,390 --> 00:00:03,770
actually has a bug.

4
00:00:03,770 --> 00:00:08,060
In rare circumstances, GetString, per
its own documentation, can return

5
00:00:08,060 --> 00:00:09,390
something other than a string.

6
00:00:09,390 --> 00:00:12,700
Specifically, a sentinel, a special
value called null--

7
00:00:12,700 --> 00:00:14,080
N-U-L-L.

8
00:00:14,080 --> 00:00:17,350
>> Null signifies that generally, something
went wrong whereby in this

9
00:00:17,350 --> 00:00:20,340
case, the user might have typed in such
a big string that it wouldn't fit

10
00:00:20,340 --> 00:00:23,610
in memory, and so GetString might
return null in that case.

11
00:00:23,610 --> 00:00:26,650
>> Or it might be that the user somehow
didn't type any string at all, in

12
00:00:26,650 --> 00:00:28,570
which case no string can come back.

13
00:00:28,570 --> 00:00:31,200
So it's best that we detect
whether or not null has

14
00:00:31,200 --> 00:00:33,200
been returned as follows--

15
00:00:33,200 --> 00:00:40,270
Only if S does not equal null should
I proceed to execute this loop.

16
00:00:40,270 --> 00:00:43,520
>> In other words, if GetString happens
to return null, I'm not going to

17
00:00:43,520 --> 00:00:46,880
accidentally try iterating over
characters that simply are not there.

18
00:00:46,880 --> 00:00:49,597