取决于具体情况的许多可能性：

- 如果要删除的文本在行首时始终相同。只需跳过前23个字符。

这样的东西甚至可以解决问题。

  var  result = line.SubString（ 23 ）; 

- 如果要删除的部分更多是模式，RegEx（正则表达式）更有可能提供帮助。



[更新]

格式化输入后，事情看起来有点复杂，RegEx肯定是有序的。

我会构建一个RegEx来识别有趣的部分和使用replace来重构结果。

开始解决方案的示例：

  string  pattern =  @  ^ * Left Rulegd *（[^] +）*（[^] +）\ n（[^] +） 跨度>; 
 string  input =   Left Rulegd ATTR001。 PDST.MPDTMP01（A001PMTR）PROTY（01），BRPKY（A0Y）\ nAA001PMTR 0 00AF 123456A11 2011/12/14 ENT tmp; 
 string  replacement =   

1，

2，

I am trying to parse a txt file into a desired o/p so that I can open it as a CSV once parse is completed. With a little knowledge of Linq, I tried to code around parse process but I am missing something that I myself unable to figure it out. Any help is appreciated.!

Input file:

          Left Rulegd  ATTR001.PDST.MPDTMP01(A001PMTR)  PROTY(01),BRPKY(A0Y)
A001PMTR           0    00AF   123456A11  2011/12/14  ENT tmp
          Left Rulegd  ATTR001.PDST.MPDTMP01(B001PRTY)  PROTY(01),BRPKY(A0Y)
B001PRTY   1       0    12AB   7891P12    2010/08/25  AMP tmp
B234561    2       0       0   7891P12    2011/09/12  URTST tmp
          Left Rulegd  ATTR001.PDST.MPDTMP01(C001AMEF)  PROTY(01),BRPKY(A0Y)
C001AMEF           0    PZ89   123456A11  2013/11/02  AMP tmp
          Left Rulegd  ATTR001.PDST.MPDTMP01(D001AAM)  PROTY(01),BRPKY(A0Y)
D001AAM            0    OP25   123456A11  2009/02/14  ENT tmp

Desired output:

ATTR001.PDST.MPDTMP01(A001PMTR),PROTY(01),BRPKY(A0Y),123456A11,2011/12/14,ENT tmp 
ATTR001.PDST.MPDTMP01(B001PRTY),PROTY(01),BRPKY(A0Y),7891P12,2010/08/25,AMP tmp 
ATTR001.PDST.MPDTMP01(C001AMEF),PROTY(01),BRPKY(A0Y),123456A11,2013/11/02,AMP tmp 
ATTR001.PDST.MPDTMP01(D001AAM),PROTY(01),BRPKY(A0Y),123456A11,2009/02/14,ENT tmp

What I have tried:

void Main()
{
	int counter = 0;
	string line;
	string line1;
	string srchBegin = "Left Rulegd";
	char delim = ' ';
	IEnumerable<string> allRecords;

	string filePath = @"C:\Users\vgruber\Desktop\input.TXT";
	if (File.Exists(filePath))
	{
		allRecords = File.ReadLines(filePath);
	}
	else
	{
		Console.WriteLine("File do not exist!");
	}

	StreamReader reader = File.OpenText(filePath);
	try
	{
	
	while ((line = reader.ReadLine()) != null)
	{
		
		if (line.Contains(srchBegin))
		{
			
			var values = line.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
			var result = String.Join(",", values).Remove(0, 12);			
			Console.WriteLine(result);	
		}
		else
		{
			var values1 = line.Substring(30);
			var result1 = string.Join(",", values1);
			Console.WriteLine(result1);			
		}
	}
	reader.Close();
	}
	catch(Exception er) 
	{
		
	}
}

// Define other methods and classes here

Many possibilities depending on situation:
- if the text to remove is always the same at beginning of line. Just skip the first 23 chars.
Something like this can even do the trick.

var result = line.SubString(23);

- if the part to remove is more of a pattern, RegEx (Regular Expressions) are more likely to help.

[Update]
After formatting the input, it appear that things are a little more complicated and RegEx are definitely on order.
I would build a RegEx to identify interesting parts with groups and use replace to recompose the result.
Example with beginning of solution:

string pattern =  @"^ *Left Rulegd *([^ ]+) *([^ ]+)\n([^ ]+)";
string input = "          Left Rulegd  ATTR001.PDST.MPDTMP01(A001PMTR)  PROTY(01),BRPKY(A0Y)\nA001PMTR           0    00AF   123456A11  2011/12/14  ENT tmp";
string replacement = "

1,

2,