可以在c＃中切换case包含方法吗？ [英] can switch case contain method in c#?

问题描述

我正在制作一个计算器，我想简单地传递一个方法以防万一？但我仍然无法做到这一点？我的意思是我不想要执行任何类型的动作，以防这是为什么我有制作方法，但它不工作/

你可以指导我...感谢你的...

解决方案

更好的是你看到下面的链接。



http://www.homeandlearn.co.uk/csharp/csharp_s2p15.html [ ^ ]

您可以在Switch / Case子句中的Case块中执行任何操作在任何方法中做。当然，您无法在Switch / Case块中定义类，方法或结构，就像您无法在标准方法中定义它们一样（除非您使用反射或Lambda表达式做了一些非常深奥的东西，所以（））但是，你为什么要这样做？



使用Switch / Case子句几乎是经典计算器示例中的标准.NET书籍给出：例如，如果我创建一组按钮，并将每个按钮的文本设置为一些基本计算，然后将相同的Click EventHandler分配给所有按钮：< pre lang =cs> // 假设您有一个TextBox，'tBoxResult，
// 您希望显示计算结果：
private void CalcBtnClick（ object sender，EventArg e）
{
按钮buttonClicked =发送者 as 按钮;

// 确保我们有一个有效的按钮！
if （buttonClicked == null ） throw new ArgumentException（ 传递给CalcBtnClick的参数不是Type'按钮）;

// 此处的代码，用于获取当前要处理的操作数，
// 如果需要，可以将它们从字符串转换为double
// 仅用于测试：假设参数位于：
double arg1 = 10 。 0 ;
double arg2 = 20 。 0 ;

switch （buttonClicked.Text）
{
case +：
// add
tBoxResult.Text =（arg1 + arg2）.ToString（）;
break ;
case - ：
// subtract
tBoxResult.Text =（arg1 - arg2）。的ToString（）;
break ;
case * ：
// multiply
tBoxResult.Text =（arg1 * arg2）。的ToString（）;
break ;
}
}

使用包含按钮作为键的字典和Funcs（以Lambda表达式形式的方法），有一种更优雅的方法作为值，但它是.NET的一个非常先进的用途。 根据要求我将在此处演示。

一个swtich表达式或case标签必须是bool，char，string，integral，enum only

方法，任何其他类型都不能使用。



参考：

link [ ^ ]

i am making a calculator where i want simply pass a method in case? but still i am not able to do that? i mean i dont want perform any kind of action in case that's why i have make method but it not working/
can u plz guid me.. Thanks for in afvance...

解决方案

better u see that below link.

http://www.homeandlearn.co.uk/csharp/csharp_s2p15.html[^]

You can do anything in a Case block inside a Switch/Case clause that you can do in any method. Of course, you can't define a class, method, or struct in a Switch/Case block, just as you can't define those inside a standard method (unless you did some very esoteric stuff with reflection or Lambda Expressions, and so forth) ... but, why would you ever want to do that ?

Use of a Switch/Case clause is almost a standard in the classic Calculator example that many .NET books give: for example, if I create a set of Buttons, and set the text of each one of them to some basic calculation, and then assign the same Click EventHandler to all of them:

// assume you have a TextBox, 'tBoxResult, 
// where you want the result of the calculation displayed:
private void CalcBtnClick(object sender, EventArgs e)
{
    Button buttonClicked = sender as Button;

    // make sure we have a valid button !
    if(buttonClicked == null) throw new ArgumentException("argument passed to CalcBtnClick is not Type 'Button");

    // code here to get current operands to be processed,
    // if necessary convert them from strings to double
    // for testing only: assume arguments are in:
    double arg1 = 10.0;
    double arg2 = 20.0;

    switch (buttonClicked.Text)
    {
        case "+":
            // add
            tBoxResult.Text = (arg1 + arg2).ToString();
            break;
        case "-":
            // subtract
            tBoxResult.Text = (arg1 - arg2).ToString();
            break;
        case "*":
            // multiply
            tBoxResult.Text = (arg1 * arg2).ToString();
            break;
    }
}

There is a more "elegant" way to do this using a Dictionary holding Buttons as Keys, and Funcs (methods ... in the form of Lambda Expressions) as Values, but it is a very advanced use of .NET. On request I will demonstrate that here.

A swtich expression or case label must be a bool,char,string,integral,enum only
methods ,any other types cannot be used.

reference :
link [^]

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