尝试从以给定变量开头和结尾的文本文件中获取

Question

以下两种情况均不起作用。我想从文本文件中提取可以通过指定行的开头和结尾来选择的特定部分。

1. 情况如下：

using (StreamReader reader = new StreamReader("C:/Users/david/Desktop/20180820.log",Encoding.Default))
{
    Console.WriteLine("From:");
    string a = (Console.ReadLine());
    Console.WriteLine(" To:");
    string b = (Console.ReadLine());   
    while (!reader.EndOfStream)
    {
        var line = reader.ReadLine();
        if (line.StartsWith(a) && (line.EndsWith(b)))
        {
            Console.WriteLine(line);
        }
    }
}

2. 使用正则表达式的情况

string line;
while ((line = reader.ReadLine()) != null)
{
    string regex12 = a.ToString() + b.ToString(); 
    Match m = Regex.Match(line,regex12);
    string s = Regex.Match(line, regex12).Groups[0].Value;
    Console.WriteLine(s);
    if (m.Success) 
    {
        string n = m.Groups[0].Value;
        Console.WriteLine(n);
    }
}

如果有人能解决我的问题，我将非常感激。

Answer 1

基于注释的更新

根据评论，您似乎正在尝试解析特定格式的文件，因此使用非通用解决方案会更好。同样，看起来文本被分成多行，而不是您在注释中共享的一行。

[00:09:08.870] text... 
[00:09:08.886] text... 
[00:09:08.886] text... 
[00:09:10.448] text... 
[00:09:10.464] text... 
[00:09:10.526] text... 
[00:09:11.886] text... 
[00:09:11.901] text... 
[00:09:11.980] text... 
[00:09:12.026] text...

在这种情况下，您可以使用以下内容。

var reader = File.OpenText(filePAth);
var startLineDetected = false;
var startWord = "00:09:08.870";
var endWord =  "00:09:12.026";
var strBuilder = new StringBuilder();
while(!reader.EndOfStream)
{
    var newLine = reader.ReadLine();
    if(newLine.Contains($"[{startWord}") && !startLineDetected)
    {
        startLineDetected = true;
    }

    if(newLine.Contains($"[{endWord}") && startLineDetected)
    {
        strBuilder.AppendLine(newLine);
        break;
    }

    if(startLineDetected)
    {
        strBuilder.AppendLine(newLine);
    }
}
var resultData = strBuilder.ToString();

基于OP的原始答案

您可以执行以下操作。

var reader = File.OpenText(filePAth);
var startLineDetected = false;
var startWord = // startWord;
var endWord =  // endWord;
var strBuilder = new StringBuilder();
while(!reader.EndOfStream)
{
    var newLine = reader.ReadLine();


    if(newLine.Contains(startWord) && !startLineDetected)
    {
        startLineDetected = true;
        newLine = newLine.Substring(newLine.IndexOf(startWord));
    }

    if(newLine.Contains(endWord) && startLineDetected)
    {
        newLine = newLine.Substring(0,newLine.IndexOf(endWord) + endWord.Length);
        strBuilder.Append(newLine);
        break;
    }


    if(startLineDetected)
    {
        strBuilder.Append(newLine);
    }
}
var resultData = strBuilder.ToString();