C＃语法里面问号 [英] question mark inside C# syntax

问题描述

可能重复：结果
的优点：（三元）运算符

我是查看此freesource库，我看到了这个奇怪的 - 至少对我来说 - 语法

I'm viewing this freesource library and I saw this weird - at least for me - syntax

*currFrame = ( ( diff >= differenceThreshold ) || ( diff <= differenceThresholdNeg ) ) ? (byte) 255 : (byte) 0;

的 currFrame是类型字节的

差异，differenceThreshold和differenceThresholdNeg是int类型的。

diff, differenceThreshold and differenceThresholdNeg are of type Int.

什么是问号呢？ ，这是什么奇怪的分配句话想什么意思？

What does the question mark do ? , what is this weird assign sentence suppose to mean ?

在此先感谢

推荐答案

在条件运算符（？:)返回根据布尔表达式的值两个值之一。以下是条件运算符的语法。

The conditional operator (?:) returns one of two values depending on the value of a Boolean expression. Following is the syntax for the conditional operator.

condition ? first_expression : second_expression;

C＃参考：的 http://msdn.microsoft.com/en-us/library/ty67wk28.aspx

C# reference: http://msdn.microsoft.com/en-us/library/ty67wk28.aspx

在你的情况currFrame如果将分配值为255（DIFF> = differenceThreshold）|| （DIFF< = differenceThresholdNeg）是真正，否则值为0将被分配

In your case currFrame will be assigned a value of 255 if ( diff >= differenceThreshold ) || ( diff <= differenceThresholdNeg ) is true, otherwise value 0 will be assigned.

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