C# – Return Lines Matching String

using System;
using System.IO;
using System.Collections.Generic;
using System.Text.RegularExpressions;

class ReturnLines
{
static void Main(string[] args)
{
const string pattern = @"test", filename = @"c:\data.txt";

List<string> lines = GetLinesWithMatch(File.ReadAllLines(filename), pattern);

foreach (var item in lines)
{
Console.WriteLine(item);

}

Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}

public static List<string> GetLinesWithMatch(string[] lines, string pattern)
{
Regex rx = new Regex(pattern);
List<string> matchedLines = new List<string>();
foreach (var line in lines)
{
if (rx.IsMatch(line))
{
matchedLines.Add(line);
}
}

return (matchedLines);
}
}

Output and data.txt file

Notes

https://docs.microsoft.com/en-us/dotnet/api/system.text.regularexpressions.regex?view=netframework-4.8

 

tags: MrNetTek