CopyTo Method (String)
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FileInfo.CopyTo Method (String)


Copies an existing file to a new file, disallowing the overwriting of an existing file.

Namespace:   System.IO
Assembly:  mscorlib (in mscorlib.dll)

public FileInfo CopyTo(
	string destFileName


Type: System.String

The name of the new file to copy to.

Return Value

Type: System.IO.FileInfo

A new file with a fully qualified path.

Exception Condition

destFileName is empty, contains only white spaces, or contains invalid characters.


An error occurs, or the destination file already exists.


The caller does not have the required permission.


destFileName is null.


A directory path is passed in, or the file is being moved to a different drive.


The directory specified in destFileName does not exist.


The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.


destFileName contains a colon (:) within the string but does not specify the volume.

Use the CopyTo method to allow overwriting of an existing file.


Whenever possible, avoid using short file names (such as XXXXXX~1.XXX) with this method. If two files have equivalent short file names then this method may fail and raise an exception and/or result in undesirable behavior

The following example demonstrates both overloads of the CopyTo method.

using System;
using System.IO;

class Test

    public static void Main()
        string path = @"c:\SoureFile.txt";
        string path2 = @"c:\NewFile.txt";
        FileInfo fi1 = new FileInfo(path);
        FileInfo fi2 = new FileInfo(path2);

            // Create the source file.
            using (FileStream fs = fi1.Create()) { }

            //Ensure that the target file does not exist.
            if (File.Exists(path2))

            //Copy the file.f
            Console.WriteLine("{0} was copied to {1}.", path, path2);
        catch (IOException ioex)

The following example demonstrates copying one file to another file, throwing an exception if the destination file already exists.

using System;
using System.IO;

public class CopyToTest 
    public static void Main() 
            // Create a reference to a file, which might or might not exist.
            // If it does not exist, it is not yet created.
            FileInfo fi = new FileInfo("temp.txt");
            // Create a writer, ready to add entries to the file.
            StreamWriter sw = fi.AppendText();
            sw.WriteLine("Add as many lines as you like...");
            sw.WriteLine("Add another line to the output...");
            // Get the information out of the file and display it.
            StreamReader sr = new StreamReader(fi.OpenRead());
            Console.WriteLine("This is the information in the first file:");
            while (sr.Peek() != -1)
            // Copy this file to another file. The file will not be overwritten if it already exists.
            FileInfo newfi = fi.CopyTo("newTemp.txt");
            // Get the information out of the new file and display it.
            sr = new StreamReader(newfi.OpenRead());
            Console.WriteLine("{0}This is the information in the second file:", Environment.NewLine);
            while (sr.Peek() != -1)
        catch(Exception e)
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//This is the information in the first file:
//Add as many lines as you like...
//Add another line to the output...

//This is the information in the second file:
//Add as many lines as you like...
//Add another line to the output...


for reading and writing files. Associated enumerations: FileIOPermissionAccess.Read, FileIOPermissionAccess.Write

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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