在没有Foreach循环的情况下访问LINQ结果中的行? [英] Accessing Rows In A LINQ Result Without A Foreach Loop?

问题描述

对于我编写的每个LINQ查询，我总是使用foreach循环来遍历结果.现在，我有一个程序，要获取结果的前50行，对这些行进行一些计算，然后获取结果的后50行，等等.

For every single LINQ query I've written, I've always used a foreach loop to go through the result. Now, I have a program where I want to get the first 50 rows of the result, do some calculations with those rows, then get the next 50 rows of the result etc.

使用LINQ和C#做到这一点的最佳标准方法是什么?

What is the good standards way to do this using LINQ and C#?

推荐答案

.Skip().Take()将是最好的方法.例如:

.Skip().Take() is going to be the best method (as far as clarity goes) in this case. For example:

var results = db.Table.Select(); // Your query here

int rowCount = results.Count(); // Count rows once and store

for(int i = 0; i <= rowCount; i += 50)
{
    var paged = results.Skip(i).Take(50);

    // do the calculations with the groups of 50 here
}

值得注意的是，即使这看起来更加清晰(您从结果中取出50个组)，但是每次调用Skip()和Take()时，都有可能需要再次对集合进行枚举...实际上比简单地使用foreach一次枚举结果效率低.

It is worth noting that even though this seems more clear (you're taking groups of 50 from the results), each time you call Skip() and Take() there's a chance that the collection has to be enumerated over again...which is actually less efficient than simply using foreach to enumerate over the results a single time.

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