Xin chào các bạn, bài viết hôm nay mình chia sẻ các bạn đoạn code giùm để tìm và lấy tất cả các email từ trong 1 file text.

[C#] Extract Email Addresses from Text File

Ví dụ: các bạn có file text input.txt như sau

This text file contains eddiejackson1@test.com AA aa BB bb.
This text file contains eddiejackson2@test.com CC cc DD dd.
This text file contains eddiejackson3@test.com EE ee FF ff.
This text file contains eddiejackson4@test.com 1234567890.
This text file contains eddiejackson5@test.com 1234567890.
This text file contains eddiejackson6@test.com 1234567890.

và kết quả chúng ta mong muốn là lấy danh sách email từ file input.txt xuất ra file text output.txt như sau:

eddiejackson1@test.com
eddiejackson2@test.com
eddiejackson3@test.com
eddiejackson4@test.com
eddiejackson5@test.com
eddiejackson6@test.com

Source code extract email from text file C#:

using System;
using System.IO;
using System.Text.RegularExpressions;
using System.Text;
 
class ExtractEmailAddresses
{
 
    public static void Main()
    {
        // read data
        string input = File.ReadAllText(@"C:\csharp\return_email\input.txt");
        //Console.Write(input);
 
        // email address pattern
        const string Pattern =
           @"(([\w-]+\.)+[\w-]+|([a-zA-Z]{1}|[\w-]{2,}))@"
           + @"((([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\."
             + @"([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])\.([0-1]?[0-9]{1,2}|25[0-5]|2[0-4][0-9])){1}|"
           + @"([a-zA-Z]+[\w-]+\.)+[a-zA-Z]{2,4})";
         
        // set up regex instance with options
        Regex emailPattern = new Regex(Pattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
        
        // perform match
        MatchCollection emailMatches = emailPattern.Matches(input);
 
        // set up our string builder
        StringBuilder sb = new StringBuilder();
 
        // build the list
        Console.WriteLine("---EXTRACTED EMAIL ADDRESSES---");
        foreach (Match emailMatch in emailMatches)
        {
            // add address to builder
            sb.AppendLine(emailMatch.Value);
 
            // display to console
            Console.WriteLine("\n {0}", emailMatch.Value);
 
        }
 
        // write to file
        File.WriteAllText(@"C:\csharp\return_email\output.txt", sb.ToString());
 
        // exit
        Console.WriteLine("\nPress any key to continue...");
        Console.ReadKey();
    }
}

Thanks for watching!