Func<>与委托和lambda表达式 [英] Difference between Func<> with delegate and lambda expression

问题描述

在深入自己的C＃的更高级功能的同时，我遇到了一些代码，我不完全相同的区别。这是关于这两行：

  Func< string，int> giveLength =（text => text.Length）; 
  

和

  Func< string，int> giveLength = delegate（string text）{return text.Length; }; 
  

可以以相同的方式使用：

  Console.WriteLine（giveLength（A random string。））; 
  

所以基本上这两行有什么区别？这些线是否编译成相同的CIL？

解决方案

基本上是一样的。他们都是C＃规范术语中的匿名函数。

Lambda表达式通常更简洁，也可以转换为 表达式树 ，这对于进程外关键LINQ。

如果您不在意，匿名方法允许您删除参数列表。例如：

  EventHandler handler = delegate {
 Console.WriteLine（发件人和参数无关紧要） ; 
}; 
  

鉴于后一点的需求很少，匿名方法正在成为现代C＃中的濒危物种。 Lambda表达式更常见。

while deepening myself to more advanced features of C#, I came across some code, which I didn't exactly know the difference of. It's about these two lines:

Func<string, int> giveLength = (text => text.Length);

and

Func<string, int> giveLength = delegate(string text) { return text.Length; };

This can be used in the same way:

Console.WriteLine(giveLength("A random string."));

So basically.. What is the difference of these two lines? And are these lines compiling to the same CIL?

解决方案

They're the same, basically. They're both anonymous functions in C# specification terminology.

Lambda expressions are generally more concise, and can also be converted to expression trees, which are crucial for out-of-process LINQ.

Anonymous methods allow you to drop the parameter list if you don't care. For example:

EventHandler handler = delegate { 
    Console.WriteLine("Sender and args don't matter");
};

Given how rarely the latter point is required, anonymous methods are becoming an endangered species in modern C#. Lambda expressions are much more common.

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