CODEWITHSUNDEEP
c#
user6815384
user6815384

Reputation: 219

Read a line after specific word using c#

I am attempting to parse a text file and have encountered a problem. I needed to read a line after the word "MESSAGE".

The file would contain sample data like the following.

MESSAGE
2005 Repair auto axle driver side.

MESSAGE
1508 Repair hydrolic suspension.

In this case I wanted to read the lines beginning with 2005 and 1508.

Here is my code

List<Record> records = new List<Record>();

using (FileStream fs = new FileStream("SampleData.txt", FileMode.Open)) 
{
    using (StreamReader rdr = new StreamReader(fs))
    {
        string tempreadline;
        tempreadline = rdr.ReadLine();
        while (tempreadline != null)
        {
            if (tempreadline.Contains("MESSAGE")
               {
                     // what do I do here?
                     // skip "MESSAGE" line and read the next line
               }
        }
     }
}

Any suggestions? Thank you!

Upvotes: 1

Views: 2325

Answers (2)

slaesh
slaesh

Reputation: 16917

METHOD 1

Using your approach.

Console.WriteLine("METHOD 1");

var records = new List<string>();

using (var fs = new FileStream("d:\\SampleData.txt", FileMode.Open))
{
    using (var rdr = new StreamReader(fs))
    {
        var msgFound = false;
        while (!rdr.EndOfStream)
        {
            var tempreadline = rdr.ReadLine();
            if (tempreadline.Contains("MESSAGE"))
            {
                msgFound = true;
            }
            else if (msgFound && !string.IsNullOrEmpty(tempreadline))
            {
                records.Add(tempreadline);
                msgFound = false;
            }
        }
    }
}

records.ForEach(r => Console.WriteLine(r));

METHOD 2

Assuming your text is a single string.

Console.WriteLine("METHOD 2");

var text = File.ReadAllText("d:\\SampleData.txt");
records = text.Split(new[] { "MESSAGE" }, StringSplitOptions.RemoveEmptyEntries)
              .Select(t => t.Trim(' ', '\r', '\n'))
              .Where(t => !string.IsNullOrEmpty(t))
              .ToList();

records.ForEach(r => Console.WriteLine(r));

METHOD 3

Assuming your text is a list of strings.

Console.WriteLine("METHOD 3");

var texts = File.ReadLines("d:\\SampleData.txt");
records = texts.Where(t => !string.IsNullOrEmpty(t) && !t.StartsWith("MESSAGE"))
               .ToList();

records.ForEach(r => Console.WriteLine(r));

METHOD 4

Using regular expressions.

Console.WriteLine("METHOD 4");

records = new Regex(@"^MESSAGE[\s]*$", RegexOptions.IgnoreCase | RegexOptions.Multiline)
                .Split(text)
                .Select(t => t.Trim(' ', '\r', '\n'))
                .Where(t => !string.IsNullOrEmpty(t))
                .ToList();

records.ForEach(r => Console.WriteLine(r));

Upvotes: 3

Codor
Codor

Reputation: 17605

If the desired content is in a file, you could use a combination of the File.ReadAllLines method, which is described here, and a Linq extension method, as follows. The array DesiredLines can the be processed further.

var DesiredLines = File.ReadAllLines("C:\FileName.txt")
                       .Where( iLine => iLine != "MESSAGE" && iLine != "")
                       .ToArray();

Upvotes: 0

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