1
00:00:05,590 --> 00:00:08,899
In this video, we'll learn
about c++ conditional operator.

2
00:00:09,580 --> 00:00:11,700
This is a really neat
and very useful operator.

3
00:00:12,349 --> 00:00:15,030
The operator is represented
by the question mark and the

4
00:00:15,030 --> 00:00:17,890
colon symbols, but they aren't
used next to one another.

5
00:00:18,680 --> 00:00:21,610
The conditional operator is a
ternary operator, which means that

6
00:00:21,610 --> 00:00:23,390
it operates on three operands.

7
00:00:23,790 --> 00:00:26,730
The first operand is the
conditional expression, which

8
00:00:26,730 --> 00:00:28,079
is usually in parentheses.

9
00:00:28,849 --> 00:00:32,170
The conditional expression is
evaluated first and it must evaluate

10
00:00:32,189 --> 00:00:34,199
to a Boolean or true false value.

11
00:00:35,080 --> 00:00:37,980
Then we follow the conditional
expression with the question mark part

12
00:00:37,980 --> 00:00:41,860
of the conditional operator, followed
by expression one, then the colon

13
00:00:41,860 --> 00:00:43,790
part, followed by expression two.

14
00:00:44,300 --> 00:00:46,960
This may sound complicated
but it's really super simple.

15
00:00:47,559 --> 00:00:49,510
The conditional
expression is evaluated.

16
00:00:49,870 --> 00:00:53,589
If it's true, then the expression
returns the value of expression one.

17
00:00:53,850 --> 00:00:57,370
If it's false, then the expression
returns the value of expression 2.

18
00:00:58,380 --> 00:01:01,720
You can see it's like an if else
construct in a single expression.

19
00:01:02,660 --> 00:01:05,880
While this operator is very
handy, it's also easy to abuse.

20
00:01:06,210 --> 00:01:08,979
Best practice is to never
nest a conditional operator

21
00:01:08,980 --> 00:01:10,280
expression within another one.

22
00:01:10,539 --> 00:01:13,530
This leads to if else if logic
that quickly becomes unreadable

23
00:01:13,570 --> 00:01:15,270
and difficult to manage.

24
00:01:15,630 --> 00:01:17,740
Let's see some examples of
the conditional operator.

25
00:01:19,360 --> 00:01:22,899
In this example, we have
variables a and b initialized

26
00:01:22,929 --> 00:01:24,460
to 10 and 20, respectively.

27
00:01:24,690 --> 00:01:28,999
We also have score initialized to
92, and result initialized to 0.

28
00:01:29,690 --> 00:01:32,270
The first assignment statement
uses the conditional operator

29
00:01:32,270 --> 00:01:33,380
on the right hand side.

30
00:01:33,970 --> 00:01:36,250
First, we evaluate a greater than b.

31
00:01:36,520 --> 00:01:40,759
If a is greater than b, then the
value of a is assigned to the result.

32
00:01:41,300 --> 00:01:44,929
If a is not greater than b, then
we assign the value of b to result.

33
00:01:45,120 --> 00:01:45,640
That's it.

34
00:01:45,650 --> 00:01:46,979
You see it's very straightforward.

35
00:01:47,230 --> 00:01:49,940
You can see this works exactly
like an if else statement,

36
00:01:50,140 --> 00:01:51,289
but it's more concise.

37
00:01:52,390 --> 00:01:55,770
The second example evaluates
if a is less than b.

38
00:01:56,340 --> 00:02:00,070
If this is true, then the value of
b minus a is assigned to result.

39
00:02:00,500 --> 00:02:03,429
Otherwise, the value of a
minus b is assigned to result.

40
00:02:04,009 --> 00:02:06,460
In the third example, we're
using the conditional operator

41
00:02:06,460 --> 00:02:08,440
to avoid a divide by 0 error.

42
00:02:09,008 --> 00:02:11,330
First, we check if
b is not equal to 0.

43
00:02:11,850 --> 00:02:16,810
If this is true, then we divide a by b
and assign the result back to result.

44
00:02:17,889 --> 00:02:20,099
Otherwise, we simply
assign 0 to the result.

45
00:02:20,630 --> 00:02:24,299
Notice how we're avoiding a divide
by 0 error by making sure that b

46
00:02:24,299 --> 00:02:26,400
is not equal to 0 before we divide.

47
00:02:27,150 --> 00:02:30,980
Finally, we often see the conditional
operator used in output statements.

48
00:02:31,520 --> 00:02:34,410
In this case, we check if
score is greater than 90.

49
00:02:34,570 --> 00:02:36,320
And if it is, we display excellent.

50
00:02:36,389 --> 00:02:37,800
Otherwise, we display good.

51
00:02:38,820 --> 00:02:41,819
You can see the conditional operator
can be very handy and easy to read and

52
00:02:41,820 --> 00:02:43,270
understand when it's used this way.

53
00:02:43,850 --> 00:02:46,140
Let's head over to the IDE
and see it in live code.

54
00:02:47,820 --> 00:02:51,329
Okay, so now I'm in CodeLite,
I'm in the section 9 workspace in

55
00:02:51,330 --> 00:02:53,149
the conditional operator project.

56
00:02:53,570 --> 00:02:56,980
And what I'd like to do is just go
over a couple of real simple examples

57
00:02:56,980 --> 00:02:58,510
of using the conditional operator.

58
00:02:58,910 --> 00:03:01,970
First, we'll write it using a regular
if else statement, then we'll write

59
00:03:01,970 --> 00:03:03,490
it using the conditional operator.

60
00:03:03,650 --> 00:03:05,510
Okay, so let's get started.

61
00:03:05,590 --> 00:03:09,480
Let's create a variable here, we'll
call it num, and this is what the

62
00:03:09,480 --> 00:03:12,560
user is going to enter an integer
into we're going to save it into here.

63
00:03:12,900 --> 00:03:21,460
We'll prompt the user to
enter an integer, and we'll

64
00:03:21,460 --> 00:03:22,859
read that integer into num.

65
00:03:25,310 --> 00:03:26,630
Okay, simple as that now.

66
00:03:26,630 --> 00:03:28,910
What we want to know is we want
to know whether the integer they

67
00:03:28,910 --> 00:03:31,019
typed in is even or it's odd.

68
00:03:31,380 --> 00:03:33,319
So let's use a simple
if else statement.

69
00:03:33,339 --> 00:03:39,090
We'll say if the number they
entered mod 2 is equal to 0.

70
00:03:40,780 --> 00:03:45,090
Okay, In this case, we're dividing by
2, and we're looking at the remainder.

71
00:03:45,090 --> 00:03:48,150
So obviously, if it's an even
number, the remainder will be 0.

72
00:03:48,160 --> 00:03:49,130
That's what we're testing.

73
00:03:49,830 --> 00:03:51,820
So in this case, we'll just say cout.

74
00:03:53,420 --> 00:03:59,170
Let's say num is even.

75
00:04:02,970 --> 00:04:06,270
And in the else case,
obviously, it has to be odd.

76
00:04:15,490 --> 00:04:20,339
Okay, so that's real simple logic here.

77
00:04:20,470 --> 00:04:21,668
Let's test this out.

78
00:04:29,279 --> 00:04:31,060
Yeah, I forgot the
l in in the endline.

79
00:04:33,520 --> 00:04:36,170
Okay, so an even integer,
let's say we want to type in 6.

80
00:04:36,340 --> 00:04:37,210
6 is even.

81
00:04:37,250 --> 00:04:37,930
That's correct.

82
00:04:38,240 --> 00:04:39,690
We'll run it one more time with 7.

83
00:04:40,770 --> 00:04:42,869
7 is odd simple as that.

84
00:04:43,759 --> 00:04:47,120
Now let's rewrite this if else
statement just using a simple

85
00:04:47,120 --> 00:04:50,970
conditional operator, that's
inside us of the output statement.

86
00:04:51,240 --> 00:04:56,040
So we'll say cout, and
we'll say same thing num.

87
00:04:56,389 --> 00:04:58,390
Now here's where we'll put
the conditional operator.

88
00:05:00,940 --> 00:05:06,529
Num is and right here is where
we'll put the conditional operator.

89
00:05:06,870 --> 00:05:11,559
Okay, so in this case, we need to
wrap this up, and we'll put the

90
00:05:11,600 --> 00:05:13,140
conditional operator right in here.

91
00:05:13,140 --> 00:05:17,570
So we're going to test to see
if num mod 2 is equal to 0.

92
00:05:18,219 --> 00:05:21,579
Okay, if that is the case, then
I've got my question mark, which

93
00:05:21,620 --> 00:05:28,730
gives me the true side and I'll
just say even and the colon odd.

94
00:05:31,260 --> 00:05:32,190
That's it.

95
00:05:33,110 --> 00:05:34,820
And we'll end this with
a new line as well.

96
00:05:37,110 --> 00:05:38,719
And let's run this and
see what it looks like.

97
00:05:40,719 --> 00:05:43,510
So we'll put in 2, and we can
see both of those statements

98
00:05:43,510 --> 00:05:46,000
fire because we've got the
regular if else statement going.

99
00:05:46,560 --> 00:05:48,280
And let's try to run it again with 3.

100
00:05:50,660 --> 00:05:51,580
There we go.

101
00:05:51,770 --> 00:05:53,640
Now let's see what's
really going on here.

102
00:05:54,620 --> 00:06:00,300
In this case, again we are testing
to see if the number is even.

103
00:06:00,650 --> 00:06:05,840
If this is true, then this piece is
the one that's going to remember.

104
00:06:05,840 --> 00:06:08,760
We've got an output operator
here an insertion operator.

105
00:06:08,960 --> 00:06:12,629
So this is going to be replaced
this whole thing right here, will be

106
00:06:12,630 --> 00:06:14,460
replaced with even, the string even.

107
00:06:15,179 --> 00:06:17,369
If it's false, it'll
be replaced with odds.

108
00:06:17,369 --> 00:06:19,330
So we've got the same
thing going on here, right.

109
00:06:19,330 --> 00:06:20,090
Num is even.

110
00:06:20,270 --> 00:06:23,539
Numb is odd, except that it's
all in one statement like that.

111
00:06:24,080 --> 00:06:26,580
This may you may be wondering why
in the world would you do this.

112
00:06:26,630 --> 00:06:30,730
Well, a lot of times it's really
handy to not have this sort of

113
00:06:30,730 --> 00:06:34,010
logic here but rather put something
right in a print statement.

114
00:06:34,010 --> 00:06:36,359
So suppose we've got some sort
of output statement, and we've

115
00:06:36,360 --> 00:06:39,000
got some kind of looping thing
going on and every 10th time

116
00:06:39,680 --> 00:06:42,370
I need to do something, I need
to print something different.

117
00:06:42,840 --> 00:06:45,930
It's real handy to use this
operator in that context because

118
00:06:45,940 --> 00:06:47,599
it makes your code a lot cleaner.

119
00:06:47,889 --> 00:06:51,199
And if you use it properly, like
this, it's really easy to understand.

120
00:06:51,520 --> 00:06:55,210
Okay, let's do another example,
and I'll comment this out here.

121
00:06:58,770 --> 00:07:00,550
And let's just do a real
simple example it's just

122
00:07:00,550 --> 00:07:01,940
going to compare two integers.

123
00:07:02,080 --> 00:07:03,850
Okay, so we need those
two integers here.

124
00:07:04,260 --> 00:07:07,550
We'll call them num1 and num2.

125
00:07:11,949 --> 00:07:19,350
And we'll tell the user to enter
to integers separated by a space.

126
00:07:23,889 --> 00:07:28,960
Okay, and we'll read into those
two integers, num1 and num2.

127
00:07:30,490 --> 00:07:34,740
All right, so in this case, I want
to display the largest and the

128
00:07:34,740 --> 00:07:36,240
smallest of those two integers.

129
00:07:36,270 --> 00:07:38,870
But I want to do it using
the conditional operator.

130
00:07:39,410 --> 00:07:41,260
So the first thing we need to
do is we need to see if the

131
00:07:41,260 --> 00:07:42,540
integers are the same, right.

132
00:07:42,559 --> 00:07:44,900
If they are the same, then
we'll just say they're the same.

133
00:07:44,900 --> 00:07:46,460
There is no largest or smallest.

134
00:07:46,619 --> 00:07:48,239
So let's do that logic first.

135
00:07:48,359 --> 00:07:55,200
So we'll say if num1 is not
equal to num2, in this case,

136
00:07:55,330 --> 00:07:57,769
we want to say, okay, one's
bigger than the other which is

137
00:07:57,770 --> 00:07:59,250
biggest which is smallest, right.

138
00:07:59,320 --> 00:08:01,739
The else case means
that they're the same.

139
00:08:02,090 --> 00:08:03,609
So let's handle that case first.

140
00:08:03,719 --> 00:08:08,610
So we'll just say cout and
we'll just say something like

141
00:08:08,610 --> 00:08:09,600
the numbers are the same.

142
00:08:14,460 --> 00:08:15,719
And I'll put a new line at the end.

143
00:08:19,049 --> 00:08:22,169
Okay, now this is the logic
we need to figure out now.

144
00:08:22,299 --> 00:08:25,039
We need to figure out what's the
largest and what's the smallest.

145
00:08:25,180 --> 00:08:27,790
I could write an if else statement
in here a couple of times, right.

146
00:08:28,020 --> 00:08:29,960
But in this case, I'm just
going to do it right in line

147
00:08:29,960 --> 00:08:30,950
with an output statement.

148
00:08:31,020 --> 00:08:32,080
So let's do the first one.

149
00:08:32,389 --> 00:08:34,039
We'll say cout.

150
00:08:34,808 --> 00:08:37,539
And what I want to do here is I'll
just say the largest because that's

151
00:08:37,539 --> 00:08:38,760
what we're going to look for first.

152
00:08:41,650 --> 00:08:43,919
And now we'll use the
conditional operator.

153
00:08:43,940 --> 00:08:48,540
So again, I'll put the parens in
there and I'll put an end line at

154
00:08:48,540 --> 00:08:49,710
the end might as well do it now.

155
00:08:52,170 --> 00:08:57,789
Now the logic in here says,
okay let's test to see if num1

156
00:08:58,570 --> 00:09:02,220
is greater than num2, right.

157
00:09:02,330 --> 00:09:07,420
If it is, I use the conditional
operator and display num1.

158
00:09:08,120 --> 00:09:10,180
If it's not, I display num2.

159
00:09:11,010 --> 00:09:11,689
That's it.

160
00:09:11,840 --> 00:09:12,509
Simple as that.

161
00:09:14,530 --> 00:09:24,480
And over here, we'll say cout
smallest and same sort of logic.

162
00:09:26,950 --> 00:09:28,830
We'll come right into
these parens right in here.

163
00:09:29,620 --> 00:09:30,820
And what we'll do is we'll test.

164
00:09:30,830 --> 00:09:33,839
In this case, num1 less than num2.

165
00:09:35,179 --> 00:09:37,930
And if it is, num1.

166
00:09:37,930 --> 00:09:38,890
Otherwise, num2.

167
00:09:40,790 --> 00:09:41,540
Okay, that's it.

168
00:09:41,580 --> 00:09:42,760
Let's run this.

169
00:09:46,830 --> 00:09:47,779
And it says no.

170
00:09:47,790 --> 00:09:48,940
It should have been num1.

171
00:09:52,230 --> 00:09:54,199
Enter two integers
separated by a space.

172
00:09:54,230 --> 00:09:55,850
Let's do the equal case first.

173
00:09:56,400 --> 00:09:57,949
The numbers are the same, that's good.

174
00:09:59,660 --> 00:10:02,020
Let's do a 5 and 10.

175
00:10:02,160 --> 00:10:04,200
Largest is 10, smallest is 5.

176
00:10:04,590 --> 00:10:06,100
And now let's do a 10 and a 5.

177
00:10:09,730 --> 00:10:11,509
Largest is 10, smallest is still 5.

178
00:10:11,520 --> 00:10:12,040
So we're good.

179
00:10:12,309 --> 00:10:15,190
So here's a real simple example
of using the conditional operator.

180
00:10:15,370 --> 00:10:17,570
We'll use the conditional
operator in a couple places

181
00:10:17,570 --> 00:10:18,820
as the course progresses.

182
00:10:19,210 --> 00:10:22,060
And typically, it's going to be
inside the loop as we're looping

183
00:10:22,060 --> 00:10:25,250
and we want to do something
every fifth time, tenth time.

184
00:10:25,820 --> 00:10:27,839
Let's say you every fifth
time you want to print a new

185
00:10:27,839 --> 00:10:29,009
line or something like that.

186
00:10:29,309 --> 00:10:32,940
Then this makes a lot of
sense to do it inside an

187
00:10:33,230 --> 00:10:34,660
output statement like this.