Lambdas are just something that, once you get your head around, you "get" it. If you're using a delegate currently, you can replace it with a lambda. Also the System.Action<...>, System.Func<...>, and System.Predicate<...> additions are nice shortcuts. Some examples showing syntax would be helpful though (warning: they are inane but I wanted to illustrate how you can swap functions):
public static void Main()
{
// ToString is shown below for clarification
Func<int,string,string> intAndString = (x, y) => x.ToString() + y.ToString();
Func<bool, float, string> boolAndFloat = (x, y) => x.ToString() + y.ToString();
// with declared
Combine(13, "dog", intAndString);
Combine(true, 37.893f, boolAndFloat);
// inline
Combine("a string", " with another", (s1, s2) => s1 + s2);
// and multiline - note inclusion of return
Combine(new[] { 1, 2, 3 }, new[] { 6, 7, 8 },
(arr1, arr2) =>
{
var ret = "";
foreach (var i in arr1)
{
ret += i.ToString();
}
foreach (var n in arr2)
{
ret += n.ToString();
}
return ret;
}
);
// addition
PerformOperation(2, 2, (x, y) => 2 + 2);
// sum, multi-line
PerformOperation(new[] { 1, 2, 3 }, new[] { 12, 13, 14 },
(arr1, arr2) =>
{
var ret = 0;
foreach (var i in arr1)
ret += i;
foreach (var i in arr2)
ret += i;
return ret;
}
);
Console.ReadLine();
}
public static void Combine<TOne, TTwo>(TOne one, TTwo two, Func<TOne, TTwo, string> vd)
{
Console.WriteLine("Appended: " + vd(one, two));
}
public static void PerformOperation<T,TResult>(T one, T two, Func<T, T, TResult> func)
{
Console.WriteLine("{0} operation {1} is {2}.", one, two, func(one,two));
}
Mostly what confused me was the shortcut syntax, for example when using System.Action to just execute a delegate with no parameters you could use:
var a = new Action(() => Console.WriteLine("Yay!"));
Or you could do:
Action a = () => Console.WriteLine("Yay");
When you've got an Action, Func, or Predicate that takes one argument you can omit the parenthesis:
var f = new Func<int, bool>(anInt => anInt > 0);
or:
// note: no var here, explicit declaration
Func<int,bool> f = anInt => anInt > 0;
As shown above, single line lambdas do not require the return statement, though multiline Func lambdas do.
I think you will find the best way to learn how to use lambdas is to work a lot with collections and include System.Linq in your using namespaces - you will see a ton of extension methods for your collections and most of these methods allow you to exercise your knowledge of lambdas.
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LINQPad是学习LINQ的好工具
LINQPad is a good tool for learning LINQ
Lambda 就是这样一种东西，一旦你开始思考，你就会“明白”它。 如果您当前正在使用委托，则可以将其替换为 lambda。 还有
System.Action<...>、System.Func<...>和System.Predicate<...>< /code> 添加是很好的快捷方式。 一些显示语法的示例会有所帮助（警告：它们很无聊，但我想说明如何交换函数）：最让我困惑的是快捷语法，例如当使用 System.Action 只执行不带参数的委托时你可以使用：
或者你可以这样做：
当你有一个带有一个参数的
Action、Func或Predicate时，你可以省略括号:or:
代替:
or 走向极端:
如上所示，单行 lambda 不需要 return 语句，但多行
Funclambda 需要。我认为您会发现学习如何使用 lambda 的最佳方法是大量使用集合，并将 System.Linq 包含在您的 using 命名空间中 - 您将看到大量针对集合的扩展方法，其中大多数方法都允许您锻炼您的 lambda 知识。
Lambdas are just something that, once you get your head around, you "get" it. If you're using a delegate currently, you can replace it with a lambda. Also the
System.Action<...>,System.Func<...>, andSystem.Predicate<...>additions are nice shortcuts. Some examples showing syntax would be helpful though (warning: they are inane but I wanted to illustrate how you can swap functions):Mostly what confused me was the shortcut syntax, for example when using System.Action to just execute a delegate with no parameters you could use:
Or you could do:
When you've got an
Action,Func, orPredicatethat takes one argument you can omit the parenthesis:or:
instead of:
or to go to the extreme:
As shown above, single line lambdas do not require the return statement, though multiline
Funclambdas do.I think you will find the best way to learn how to use lambdas is to work a lot with collections and include System.Linq in your using namespaces - you will see a ton of extension methods for your collections and most of these methods allow you to exercise your knowledge of lambdas.
目前我发现的最好的就是这个链接。 这是一个让我们练习的测验，但我想要更多的 Lambda，而不是 LINQ。
The best that I have found is this link for the moment. It's a quiz that let met practice, but I would like something more Lambda and less LINQ.