如何使用 LINQ 计算与条件匹配的元素数量 [英] How to count the number of elements that match a condition with LINQ

问题描述

我尝试了很多方法，但对我来说最合乎逻辑的似乎是这个:

I've tried a lot of things but the most logical one for me seems this one:

int divisor = AllMyControls.Take(p => p.IsActiveUserControlChecked).Count();

AllMyControls 是 UserControls 的集合，我想知道有多少 UserControls 有 IsActiveUserControlChecked属性设置为 true.

AllMyControls is a Collection of UserControls, what I want to know is how many UserControls have the IsActiveUserControlChecked property set to true.

我在 VS 中得到的是:

What I get in VS is:

Cannot convert lambda expression to type 'int' because it is not a delegate type

我的表达有什么问题?

推荐答案

int divisor = AllMyControls.Where(p => p.IsActiveUserControlChecked).Count()

或者干脆

int divisor = AllMyControls.Count(p => p.IsActiveUserControlChecked);

由于您是初学者，因此值得一看 Enumerable 文档

Since you are a beginner, it would be worthwhile to take a look at Enumerable documentation

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