C# copy file

last modified January 21, 2024

In this article we show how to copy files in C#. The File.Copy method copies an existing file to a new file. The method is available in the System.IO namespace.

C# Copy.File synopsis

public static void Copy(string sourceFileName, string destFileName);

The first argument of the method is the source file; the second argument is the destination file.

public static void Copy(string sourceFileName, string destFileName, bool overwrite);

The overloaded method takes a third argument: overwrite. It is a boolean value which tells if the destination file can be overwritten.

C# copy file example

The following example copies a file on a disk.

var source = @"C:\Users\Jano\Documents\words.txt";
var destination = @"C:\Users\Jano\Documents\words_bck.txt";

File.Copy(source, destination);
Console.WriteLine("File copied");

The example copies a text file.

var source = @"C:\Users\Jano\Documents\words.txt";
var destination = @"C:\Users\Jano\Documents\words_bck.txt";

We define a source and destination files.

File.Copy(source, destination);

The file is copied with the File.Copy method.

$ dotnet run
File copied

$ dotnet run
Unhandled exception. System.IO.IOException: The file 'C:\Users\Jano\Documents\words_bck.txt' 
already exists.
...

If we run the example twice, we have an exception telling us that the file already exists. If we use the overloaded method and set the third parameter to true, the destination file will be overwritten.

C# copy files example

In the following example, we copy multiple files.

string sourceDir = @"C:\Users\Jano\Documents\";
string backupDir = @"C:\Users\Jano\Documents\backup\";

string[] textFiles = Directory.GetFiles(sourceDir, "*.txt");

foreach (string textFile in textFiles)
{
    string fileName = textFile.Substring(sourceDir.Length);

    File.Copy(Path.Combine(sourceDir, fileName), 
            Path.Combine(backupDir, fileName), true);
}

Console.WriteLine("Files copied");

The example copies all text files to a backup directory.

string[] textFiles = Directory.GetFiles(sourceDir, "*.txt");

We enumerate all text files in the source directory.

foreach (string textFile in textFiles)
{
    string fileName = textFile.Substring(sourceDir.Length);

    File.Copy(Path.Combine(sourceDir, fileName), 
            Path.Combine(backupDir, fileName), true);
}

In a foreach loop, we go through the list of text files and copy them. We cut the file name from the absolute path using the Substring method. The Path.Combine combines strings into a path.

Source

File.Copy method

In this article we have copied files in C#.

Author

My name is Jan Bodnar and I am a passionate programmer with many years of programming experience. I have been writing programming articles since 2007. So far, I have written over 1400 articles and 8 e-books. I have over eight years of experience in teaching programming.

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