File.ReadAllLines 或 Stream Reader

File.ReadAllLines or Stream Reader(File.ReadAllLines 或 Stream Reader)

问题描述

我们可以使用 StreamReader 或使用 File.ReadAllLines.

We can read file either by using StreamReader or by using File.ReadAllLines.

例如，我想将每一行加载到 List 或 string[] 中，以便对每一行进行进一步操作.

For example I want to load each line into a List or string[] for further manipulation on each line.

string[] lines = File.ReadAllLines(@"C:\file.txt");

foreach(string line in lines)
{
     //DoSomething(line);
}

或

using (StreamReader reader = new StreamReader("file.txt"))
{
    string line;

    while ((line = reader.ReadLine()) != null)
    {
       //DoSomething(line); or //save line into List<string>
    }
}

//if list is created loop through list here 

应用程序遇到不同大小的文本文件.偶尔会从几个 KBs 增长到 MBs.

Application come across different size of text file. Which could grow from few KBs to MBs occasionally.

我的问题是哪一种是首选方式，为什么应该优先选择其他方式?

My question is that which one is preferred way and why one should be preferred over other?

推荐答案

如果你想处理一个文本文件的每一行而不将整个文件加载到内存中，最好的方法是这样的:

If you want to process each line of a text file without loading the entire file into memory, the best approach is like this:

foreach (var line in File.ReadLines("Filename"))
{
    // ...process line.
}

这避免了加载整个文件，并使用现有的 .Net 函数来完成.

This avoids loading the entire file, and uses an existing .Net function to do so.

但是，如果由于某种原因需要将所有字符串存储在一个数组中，最好只使用 File.ReadAllLines() - 但如果您只使用 foreach 访问数组中的数据，然后使用File.ReadLines().

However, if for some reason you need to store all the strings in an array, you're best off just using File.ReadAllLines() - but if you are only using foreach to access the data in the array, then use File.ReadLines().

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