For vs. Linq - 性能 vs. 未来 [英] For vs. Linq - Performance vs. Future

问题描述

非常简短的问题.我有一个随机排序的大字符串数组(100K+ 个条目)，我想在其中找到所需字符串的第一次出现.我有两个解决方案.

Very brief question. I have a randomly sorted large string array (100K+ entries) where I want to find the first occurance of a desired string. I have two solutions.

通过阅读我可以猜测的是，for 循环"目前的性能会稍好一些(但这个边距总是会改变)，但我也发现 linq 版本更具可读性.总的来说，哪种方法通常被认为是当前的最佳编码实践，为什么?

From having read what I can my guess is that the 'for loop' is going to currently give slightly better performance (but this margin could always change), but I also find the linq version much more readable. On balance which method is generally considered current best coding practice and why?

string matchString = "dsf897sdf78";
int matchIndex = -1;
for(int i=0; i<array.length; i++)
{
    if(array[i]==matchString)
    {
        matchIndex = i;
        break;
    }
}

或

int matchIndex = array.Select((r, i) => new { value = r, index = i })
                         .Where(t => t.value == matchString)
                         .Select(s => s.index).First();

推荐答案

最佳实践取决于您的需求:

The best practice depends on what you need:

1. 开发速度和可维护性:LINQ
2. 性能(根据分析工具):手动代码

LINQ 确实通过所有间接方式减慢了速度.不要担心，因为 99% 的代码不会影响最终用户的性能.

LINQ really does slow things down with all the indirection. Don't worry about it as 99% of your code does not impact end user performance.

我从 C++ 开始，真正学会了如何优化一段代码.LINQ 不适合充分利用您的 CPU.因此，如果您认为 LINQ 查询是一个问题，请放弃它.但只有这样.

I started with C++ and really learnt how to optimize a piece of code. LINQ is not suited to get the most out of your CPU. So if you measure a LINQ query to be a problem just ditch it. But only then.

对于您的代码示例，我估计速度会降低 3 倍.通过 lambda 进行的分配(以及随后的 GC！)和间接访问真的很伤人.

For your code sample I'd estimate a 3x slowdown. The allocations (and subsequent GC!) and indirections through the lambdas really hurt.

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