blocks|key|3953120|text|switch语句使用常量值。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3953121|因此，这是有效的：|3953122|var+val+=+2;
switch+(val)
{
++++case+1:
++++++++//+Do+something+if+val+is+1.
++++++++break;
++++case+2:
++++++++//+Do+something+if+val+is+2.
++++++++break;
++++default:
++++++++//+Do+something+for+all+values+of+val+other+than+1+or+2.
++++++++break;
}|code-block|syntax|javascript|3953123|但是您希望转换处理范围的if-else。double+ranges也是如此。这是不可能的，因为switch不允许使用范围。|3953124|如果您的范围是int，您可以假设为每个流行的值编写一个case，但这绝对没有意义。|3953125|比方说，如果值在int+1-3之间，你想做一些事情，如果它在4-6之间，你想做其他事情。你可以写一些像下面这样的东西，但那将是无意义的。你最好坚持使用if-else。|3953126|var+val+=+2;
switch+(val)
{
++++case+1:
++++case+2:
++++case+3:
++++++++//+Do+something+if+val+is+between+1-3.
++++++++break;
++++case+4:
++++case+5:
++++case+6:
++++++++//+Do+something+if+val+is+between+4-6.
++++++++break;
++++default:
++++++++//+Do+something+for+all+other+values+of+val
++++++++break;
}|3953127|entityMap^0|0|6|0|0|0|C|7|K|6|1B|6|0|7|3|R|4|0|8|3|23|7|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1D|8|@$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1I|8|@]|D|@]|E|$K|L]]|$1|U|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|V|$]]

<code>switch</code> statements work with constant values.

So, this is valid:

<pre><code>var val = 2;
switch (val)
{
 case 1:
 // Do something if val is 1.
 break;
 case 2:
 // Do something if val is 2.
 break;
 default:
 // Do something for all values of val other than 1 or 2.
 break;
}
</code></pre>

But you want to convert an <code>if-else</code> that deals with ranges. That too with <code>double</code> ranges. This is not possible since a <code>switch</code> doesn't allow you to work with a range.

If your ranges are <code>int</code>, you could hypothetically write a <code>case</code> for each value in the rage, but that makes absolutely no sense.

Say, you want to do something if the value is between <code>int</code> 1-3, and something else if it's between 4-6. You could write something like the follwing, but that would be nonsensicle. You'd be better off sticking to an <code>if-else</code>.

<pre><code>var val = 2;
switch (val)
{
 case 1:
 case 2:
 case 3:
 // Do something if val is between 1-3.
 break;
 case 4:
 case 5:
 case 6:
 // Do something if val is between 4-6.
 break;
 default:
 // Do something for all other values of val
 break;
}
</code></pre>

blocks|key|3953186|text|当您想要根据单个值在多个选项之间进行选择时，switch语句非常有用。当您想要对范围进行操作时，就像您在示例中所做的那样，需要一个if语句。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3953187|下面是一个switch语句的示例。您可以看到，您在开始时指定了要打开的值，然后可以基于相等执行不同的操作。|3953188|string+color+=+"red";

switch+(color)
{
++++case+"red":
++++++++//+do+something
++++++++break;
++++case+"green":
++++++++//+do+something
++++++++break;
++++case+"blue":
++++++++//+do+something
++++++++break;
++++default:
++++++++throw+new+ColorUnknownException(color);
}|code-block|syntax|javascript|3953189|通常，switch语句是缺少设计模式的标志……但这是另一天的谈话。|3953190|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

A switch statement is useful when you want to choose between many options based on a single value. When you want to work against ranges, as you have done in your example, an if-statement is needed.

Here's an example of a switch statement... you can see that you specify the value to switch on at the start and you can then perform different actions based on equality.

<pre><code>string color = "red";

switch (color)
{
 case "red":
 // do something
 break;
 case "green":
 // do something
 break;
 case "blue":
 // do something
 break;
 default:
 throw new ColorUnknownException(color);
}
</code></pre>

Very often, a switch-statement is a sign of a missing design pattern... but that is a conversation for another day.

blocks|key|3953259|text|switch不支持float和double+values。但是，由于所有范围限制都是0.3的倍数，因此可以使用将该值除以0.3的技巧来实现您所寻求的结果，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3953260|int+Vi;
double+Vs+=+0;
private+void+btSjekkW_Click(object+sender,+EventArgs+e)
{
++++Vs+=+Convert.ToDouble(tbVindstyrke.Text);
++++Vi+=+(int)(Vs+/+0.3);
++++switch+(caseSwitch)
++++{
++++++++case+0:
++++++++case+1:
++++++++case+2:
++++++++case+3:
++++++++case+4:
++++++++case+5:
++++++++case+6:
++++++++case+7:
++++++++case+8:
++++++++++++lbWattProdusert.Text+=+0+%2B+"+W/t";
++++++++++++break;
++++++++case+9:
++++++++case+10:
++++++++case+11:
++++++++++++lbWattProdusert.Text+=+2+%2B+"+W/t";
++++++++++++break;
++++++++case+12:
++++++++case+13:
++++++++case+14:
++++++++case+15:
++++++++case+16:
++++++++case+17:
++++++++case+18:
++++++++++++lbWattProdusert.Text+=+10+%2B+"+W/t";
++++++++++default:
++++++++++++//+what+to+do+if+Vs+>+5.4
++++++++++++break;
++++++}
}|code-block|syntax|javascript|3953261|entityMap^0|0|6|9|5|M|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

<code>switch</code> doesn't work with <code>float</code> and double <code>values</code>. However, as all your range limits are multiples of 0.3, you can use the trick of dividing the value by 0.3 to achieve what you seek as follows:

<pre class="lang-cs prettyprint-override"><code>int Vi;
double Vs = 0;
private void btSjekkW_Click(object sender, EventArgs e)
{
 Vs = Convert.ToDouble(tbVindstyrke.Text);
 Vi = (int)(Vs / 0.3);
 switch (caseSwitch)
 {
 case 0:
 case 1:
 case 2:
 case 3:
 case 4:
 case 5:
 case 6:
 case 7:
 case 8:
 lbWattProdusert.Text = 0 + " W/t";
 break;
 case 9:
 case 10:
 case 11:
 lbWattProdusert.Text = 2 + " W/t";
 break;
 case 12:
 case 13:
 case 14:
 case 15:
 case 16:
 case 17:
 case 18:
 lbWattProdusert.Text = 10 + " W/t";
 default:
 // what to do if Vs &gt; 5.4
 break;
 }
}
</code></pre>

I've never used <code>switch case</code> instead of <code>if/else if</code>, and I'm wondering how to use it. I would really appreciate the help! The task is to put in an amount of wind in a textbox(tbVindstyrke) and the code should tell the user what amount of Watt per hour(W/t) the wind is generating, in a windmill. It should post the result in a label (lbWattprodusert).

I have got it to work with an <code>if</code>-statement, put as I have understood, this takes up a lot of the computers processioning power (or something). So, I would like to switch it up to a <code>switch</code>-statement.

<pre><code>double Vs = 0;
private void btSjekkW_Click(object sender, EventArgs e)
{
 Vs = Convert.ToDouble(tbVindstyrke.Text);
 if (Vs &gt;= 0 &amp;&amp; Vs &lt;= 2.4)
 lbWattProdusert.Text = 0 + " W/t";
 else if (Vs &gt;= 2.5 &amp;&amp; Vs &lt;= 3.3)
 lbWattProdusert.Text = 2 + " W/t";
 else if (Vs &gt;= 3.4 &amp;&amp; Vs &lt;= 5.4)
 lbWattProdusert.Text = 10 + " W/t";
}
</code></pre>

Changing code from if-statement to switch-statement in C#

我从来没有用过if/else if代替switch case，我想知道如何使用它。我真的很感谢你的帮助！任务是在文本框(TbVindstyrke)中输入风量，代码应该告诉用户风车中的风量是每小时多少瓦特(W/t)。它应该将结果发布到一个标签(lbWattprodusert)中。我已经让它在if-statement上工作...

问在C#中将代码从if语句更改为switch语句
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