什么是“?"做? [英] what does '?' do?

问题描述

我是c#初学者，不知道这段代码是什么?"及其结构:

Hi,
I''m a c# beginner and I don''t know what''s ''?'' and its structure in this code:

public bool IsLeapYear(int year)
{
    return year % 4 == 0 ? true : false;
}

推荐答案

这是一个运算符，其含义与以下内容相同:

This is an operator and means the same as:

public bool IsLeapYear(int year)
{
    if (year % 4 == 0)
        return true;
    else
        return false;
}

或者更简单:

or, simpler:

public bool IsLeapYear(int year)
{
    return year % 4 == 0;
}

尽管如此，我还是建议您使用:

Nonetheless I would recommend you to use:

System.DateTime.IsLeapYear(year);

因为您的代码在正确的Le年中不完整.以下是完整的代码:

because your code is incomplete for correct Leap Year. Below is the complete code:

public bool IsLeapYear(int year)
{
    if (year % 400 == 0)
        return true;
    else if (year % 100 == 0)
        return false;
    else if (year % 4 == 0)
        return true;
    else
        return false;
}

或者更简单:

or, simpler:

public bool IsLeapYear(int year)
{
    if (year % 400 == 0)
        return true;
    if (year % 100 == 0)
        return false;
    if (year % 4 == 0)
        return true;
    return false;
}

?被称为条件运算符.有关您可以在msdn上找到的更多信息:
http://msdn.microsoft.com/en-us/library/ty67wk28(VS .80).aspx [ ^ ]

和

http://msdn.microsoft.com/en-us/library/6a71f45d [ ^ ]

问候
Robert

Hi,

? is called conditional operator. more about that you can find on msdn:
http://msdn.microsoft.com/en-us/library/ty67wk28(VS.80).aspx[^]

and

http://msdn.microsoft.com/en-us/library/6a71f45d[^]

Regards
Robert

这与C语言中的三元运算符相同
它只是执行?运算符左侧的条件表达式.如果结果满足(等于true)，则在?运算符之后立即执行表达式，否则在:运算符
之后执行表达式
如果假设年份为1996

Hi this is same as ternary operator in C
It just executes the Conditional expression to the left of the ? operator. If the result satisfies (means true) it execute the expression immediate next to ? operator, otherwise it execute the expression after the : operator

if suppose year is 1996

return 1996%4==0 ? true : False

在这种情况下，编译器首先执行?运算符
左侧的条件 然后

in this the compiler first execute the conditions to the left of ? operator
then

return 0==0 ? true : False

条件为true，因此它立即在?旁边开始执行语句，在此返回true，否则在本示例中，year = 1998计算的值不等于零.它忽略紧靠?运算符的语句，并在之后执行语句:运算符为False
因此返回false

假设a = 10 b = 15

condition true so it start execute statement immediately next to ? here its return true, otherwise in this example say year =1998 the calculated value is not equal to zero It ignores the Statement immediately next to ? operator and execute the statement after the : operator which is False
hence it returns false

lets say a=10 b=15

public int void operate()
{
 c=(a>b)? a-b:a+b;
}

与
一样

this is same like

if (a>b)
c=a-b;
else 
c=a+b;

对于该条件，c ＝ 25，因为(a＞ b)为假.您可以将其用于简单的条件检查.

for this condition c=25 because (a>b) is false. you can use this for simple conditional checking.

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