C＃中包含List的Lambda表达式 [英] Lambda expressions with List in C#

问题描述

请考虑这个例子，



List< int> lst = new List< int> {1,2,3,4};

int result = lst.Aggregate（（x，y）=> x * y）;





根据文章（x，y）指定输入参数和x * y作为实现，我的疑问是，aggregate（）是列表的方法，那么它必须有内在通过它自己实现聚合，那么（x * y）指定或者更确切需要...



请提及解释lambda和单独列出的文章......



提前致谢，

Please consider this example,

List<int> lst = new List<int> { 1, 2, 3, 4 };
int result = lst.Aggregate((x, y) => x * y);


As per the articles (x,y) specifies input parameters and x*y as implementation, my doubt is, aggregate() is the method of list, then it has to have inner implementation of aggregation by its own, then what (x*y) specifies or rather needed here...

Please mention the articles explaining lambda and list separately...

Thanks in advance,

推荐答案

这里 x * y 表示元素将通过乘法汇总。



参考 - C＃Aggregate [ ^ ]。

参见示例及其输出。你会很清楚。

Here x * y indicates that the elements will be aggregated by multiplication.

Refer - C# Aggregate[^].
See the examples and their outputs. You will be clear.

Quote：

int[] array = { 1, 2, 3, 4, 5 };
	int result = array.Aggregate((a, b) => b + a);
	// 1 + 2 = 3
	// 3 + 3 = 6
	// 6 + 4 = 10
	// 10 + 5 = 15
	Console.WriteLine(result);

	result = array.Aggregate((a, b) => b * a);
	// 1 * 2 = 2
	// 2 * 3 = 6
	// 6 * 4 = 24
	// 24 * 5 = 120
	Console.WriteLine(result);

lambda几乎只是一个没有名字的方法。在=>之前的（x，y）部分在函数体之后指定参数和 x * y 部分。

在这种情况下，你正在做的是相同的of：

A lambda is pretty much just a method without a name. The (x,y) part before the => specifies the parameters and the x * y part after it is the body of the function.
In this case, what you are doing is the equivalent of:

List<int> lst = new List<int> { 1, 2, 3, 4 };
int x = 0;
for (int i = 0; i < lst.Count; i ++)
    {
    int y = lst[i];
    x = i == 0 ? y : x * y;
    }
int result = x;

仅限延迟执行（暂时不要担心）。



虚假HTML结束标签删除 - OriginalGriff [/ edit]

Only with deferred execution (don't worry about that for the moment).

[edit]Spurious HTML closing tags removed - OriginalGriff[/edit]

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