How to read particular text from file in C# [closed]

Answer 1

Assuming these are text files, just open the file and read through it searching for whatever you're searching for. When you find it, stop reading though it. The File.ReadLines() will do this for you and will not read the entire file at the start but give you lines as it goes through it.

var filename = @"c:\path\to\my\file.txt";
var searchTarget = "foo";
foreach (var line in File.ReadLines(filename))
{
    if (line.Contains(searchTarget))
    {   // found it!
        // do something...

        break; // then stop
    }
}

Otherwise, if you're not using C# 4.0, use a StreamReader and you can still accomplish the same thing in mostly the same way. Again, read up until you find your line, do something and then stop.

string line = null;
using (var reader in new StreamReader(filename))
{
    while ((line = reader.ReadLine()) != null)
    {
        if (line.Contains(searchTarget))
        {   // found it!
            // do something...

            break; // then stop
        }
    }
}

If you are searching for a specific pattern and not just a particular word, you'd need to use regular expressions in conjunction with this.