什么是IF语句OR运算符 [英] What is the OR operator in an IF statement

问题描述

在C＃中，如何指定OR：

 如果（这种或那种）{做其他事情} 
  

我找不到它的帮助。

更新：

我的代码是：

 如果（标题==用户问候语||用户名）{做的东西} 
  

和我的错误是：

错误1操作'||'不能应用于类型为布尔和字符串操作数C：\Documents和Settings\Sky查看Barns\My Documents\Visual工作室2005\Projects\FOL Ministry\FOL Ministry\Downloader.cs 63 21 FOL部

解决方案

|| 是在C＃中有条件或运营商

您可能有一个很难找到它，因为它很难寻找的东西的名字你不知道。下一次尝试做一个谷歌搜索C＃操作员，并期待在逻辑运算符。

的这是C＃运营商的列表

我的代码是：

 如果（标题==用户问候语||用户名）{做的东西}; 
  

和我的错误是：

错误1操作'||'不能为
应用于类型为布尔和
'串'C的操作数：\Documents和Settings\Sky
查看Barns\My Documents\ Visual Studio的
2005\Projects\FOL Ministry\FOL
Ministry\Downloader.cs 63 21 FOL
部

您需要这样做，而不是：

 如果（标题==用户问候语||标题==用户名）{做的东西}; 
  

OR运算符的计算结果相同的方式双方的表达式。在你的榜样，你在表达标题==用户问候语（一个布尔值），并表达操作用户名（字符串）。这些不能被不进行强制转换或转换，这就是为什么你得到错误直接结合起来。

此外，值得一提的是， || 操作员使用短路计算。这意味着，如果第一个表达式的计算结果为真正，第二个表达式不评估，因为它不必是 - 最终的结果总是会真正。有时你可以采取优化过程中利用了这一点。

最后一个快速的注意 - 我经常写我的嵌套的括号条件语句是这样的：

  IF（（标题==用户问候语）||（标题==用户名））{做的东西}; 
  

这样我可以控制的优先级和不必担心操作的顺序。这也可能是矫枉过正这里，但它是当逻辑变得复杂起来特别有用。

In C#, how do I specify OR:

if(this OR that) {do the other thing}

I couldn't find it in the help.

Update:

My code is:

if (title == "User greeting" || "User name") {do stuff}

and my error is:

Error 1 Operator '||' cannot be applied to operands of type 'bool' and 'string' C:\Documents and Settings\Sky View Barns\My Documents\Visual Studio 2005\Projects\FOL Ministry\FOL Ministry\Downloader.cs 63 21 FOL Ministry

解决方案

|| is the conditional OR operator in C#

You probably had a hard time finding it because it's difficult to search for something whose name you don't know. Next time try doing a Google search for "C# Operators" and look at the logical operators.

Here is a list of C# operators.

My code is:

if (title == "User greeting" || "User name") {do stuff};

and my error is:

Error 1 Operator '||' cannot be applied to operands of type 'bool' and 'string' C:\Documents and Settings\Sky View Barns\My Documents\Visual Studio 2005\Projects\FOL Ministry\FOL Ministry\Downloader.cs 63 21 FOL Ministry

You need to do this instead:

if (title == "User greeting" || title == "User name") {do stuff};

The OR operator evaluates the expressions on both sides the same way. In your example, you are operating on the expression title == "User greeting" (a bool) and the expression "User name" (a string). These can't be combined directly without a cast or conversion, which is why you're getting the error.

In addition, it is worth noting that the || operator uses "short-circuit evaluation". This means that if the first expression evaluates to true, the second expression is not evaluated because it doesn't have to be - the end result will always be true. Sometimes you can take advantage of this during optimization.

One last quick note - I often write my conditionals with nested parentheses like this:

if ((title == "User greeting") || (title == "User name")) {do stuff};

This way I can control precedence and don't have to worry about the order of operations. It's probably overkill here, but it's especially useful when the logic gets complicated.

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