How Can I Efficiently Read a Text File from Bottom to Top in C# Using Iterators?

Read the C#text file with the iterator efficiently reversely

Many programming tasks involve handling large text files. In the case of processing files from the end of the file, the use of the iterative -based method is more efficient than loading the entire file to the memory.

Read file -based reverse files read

.NET framework did not provide a convenient reverse read file built -in solution. To use the iterator to achieve this, you can achieve a custom class:

This type of use to generate files in the reverse order, there is no need to load the entire file to the memory.

<code class="language-csharp">public class ReverseLineReader : IEnumerable<string>
{
    private readonly Func<Stream> streamSource;
    private readonly Encoding encoding;
    private readonly int bufferSize;
    private readonly Func<long, bool, byte[]> characterStartDetector;

    public ReverseLineReader(Func<Stream> streamSource)
        : this(streamSource, Encoding.UTF8)
    {
    }

    public ReverseLineReader(Func<Stream> streamSource, Encoding encoding)
        : this(streamSource, encoding, DefaultBufferSize)
    {
    }

    internal ReverseLineReader(Func<Stream> streamSource, Encoding encoding, int bufferSize)
    {
        this.streamSource = streamSource;
        this.encoding = encoding;
        this.bufferSize = bufferSize;

        // 根据编码类型设置 characterStartDetector。
        // ...

    }

    public IEnumerator<string> GetEnumerator()
    {
        //并非所有流实现都支持查找和读取，如果出现这种情况，则返回异常。

        Stream stream = streamSource();
        try
        {
            // ...
        }
        finally
        {
            // 在此处释放流。
        }
    }

    // 在此处添加处理反向读取和处理流的其他方法。
    // ...

    // 在此处添加处理 characterStartDetector 逻辑的其他方法。
    // ...
}</code>

How to use:

By using the iterator, you can avoid loading the entire file to the memory and can handle it in the reverse order. This method is particularly useful for memory consumption is a big text file.

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