条件运算符
1
件运算符 (?:) 根据布尔型表达式的值返回两个值中的一个。条件运算符的格式如下
2![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
复制代码
4
condition ? first_expression : second_expression;
5
6![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
7
备注
8
如果条件为 true,则计算第一表达式并以它的计算结果为准;如果为 false,则计算第二表达式并以它的计算结果为准。只计算两个表达式中的一个。
9![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
10
使用条件运算符,可以更简洁、雅观地表达那些否则可能要求 if-else 结构的计算。例如,为在 sin 函数的计算中避免被零除,可编写为
11![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
12
复制代码
13
if(x != 0.0) s = Math.Sin(x)/x; else s = 1.0;
14
15![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
16
或使用条件运算符,
17![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
复制代码
19
s = x != 0.0 ? Math.Sin(x)/x : 1.0;
20
21![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
22
条件运算符为右联运算符,因此该形式的表达式
23![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
24
复制代码
25
a ? b : c ? d : e
26
27![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
按如下规则计算:
29![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
复制代码
31
a ? b : (c ? d : e)
32
33![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
34
而不是按照下面这样计算:
35![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
36
复制代码
37
(a ? b : c) ? d : e
38
39![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
40
不能重载条件运算符。
41![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
42
示例
43
复制代码
44
// cs_operator_conditional.cs
45
using System;
46
class MainClass
47
{
48
static double sinc(double x)
49
{
50
return x != 0.0 ? Math.Sin(x)/x : 1.0;
51
}
52![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
53
static void Main()
54
{
55
Console.WriteLine(sinc(0.2));
56
Console.WriteLine(sinc(0.1));
57
Console.WriteLine(sinc(0.0));
58
}
59
}
60
61![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
62
输出
63
64
0.993346653975306
65
0.998334166468282
66
1
67
68![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
34
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
35
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
36
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
37
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
38
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
39
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
40
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
41
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
42
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
43
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
44
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
45
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
46
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
47
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
48
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
49
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
50
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
51
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
52
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
53
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
54
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
55
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
56
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
57
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
58
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
59
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
60
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
61
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
62
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
63
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
64
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
65
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
66
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
67
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
68
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)