How do you merge multiple text files into a single file?

Question

Anubhav Kumar · Answer

To merge multiple text files into a single file in C#, you can use
System.IO to read each file and append its content to the target file. Here's how:
Basic Example: Merge All .txt Files in a Folder
using System.IO;
string sourceDirectory = @"C:\TextFiles";
string outputFile = @"C:\Merged\combined.txt";
// Get all .txt files in the folder
var files = Directory.GetFiles(sourceDirectory, "*.txt");
// Merge into one file
using (var output = File.CreateText(outputFile))
{
    foreach (var file in files)
    {
        string content = File.ReadAllText(file);
        output.WriteLine(content);     // Write file content
        output.WriteLine();            // Optional: blank line between files
    }
}
Variation: Append Instead of Overwriting
If you want to append to an existing file:
foreach (var file in files)
{
    File.AppendAllText(outputFile, File.ReadAllText(file) + Environment.NewLine);
}
Optional Enhancements
Add File Headers
foreach (var file in files)
{
    var fileName = Path.GetFileName(file);
    File.AppendAllText(outputFile, $"--- {fileName} ---{Environment.NewLine}");
    File.AppendAllText(outputFile, File.ReadAllText(file) + Environment.NewLine);
}
Sort Files by Name or Date
var sortedFiles = Directory.GetFiles(sourceDirectory, "*.txt")
    .Select(f =andgt; new FileInfo(f))
    .OrderBy(f =andgt; f.Name) // or .CreationTime
    .Select(f =andgt; f.FullName);
Summary
Operation
Code/Method
Read content
File.ReadAllText(path)
Write or create file
File.CreateText(path)
Append to file
File.AppendAllText(path, ...)
Merge with headers
Add file name before writing
Handle large files
Stream line by line with StreamReader/Writer

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How do you merge multiple text files into a single file?

Ravi Vishwakarma

Can you answer this question?

1 Answers

Basic Example: Merge All `.txt` Files in a Folder

Variation: Append Instead of Overwriting

Optional Enhancements

Add File Headers

Sort Files by Name or Date

Summary

Liked By

Operation	Code/Method
Read content	`File.ReadAllText(path)`
Write or create file	`File.CreateText(path)`
Append to file	`File.AppendAllText(path, ...)`
Merge with headers	Add file name before writing
Handle large files	Stream line by line with `StreamReader/Writer`