Append TimeStamp to a File Name

I have come across this problem several times in which I would like to have multiple versions of the same file in the same directory. The way I have been doing it using C# is by adding a time stamp to the file name with something like this DateTime.Now.ToString().Replace('/', '-').Replace(':', '.'). Is there a better way to do this?

You can use DateTime.ToString Method (String)

DateTime.Now.ToString("yyyyMMddHHmmssfff")

or string.Format

string.Format("{0:yyyy-MM-dd_HH-mm-ss-fff}", DateTime.Now);

or Interpolated Strings

$"{DateTime.Now:yyyy-MM-dd_HH-mm-ss-fff}"

> There are following custom format specifiers y (year), M (month), d > (day), h (hour 12), H (hour 24), m (minute), s (second), f (second > fraction), F (second fraction, trailing zeroes are trimmed), t (P.M or > A.M) and z (time zone).

With Extension Method

Usage:

string result = "myfile.txt".AppendTimeStamp();
//myfile20130604234625642.txt

Extension method

public static class MyExtensions
{
    public static string AppendTimeStamp(this string fileName)
    {
        return string.Concat(
            Path.GetFileNameWithoutExtension(fileName),
            DateTime.Now.ToString("yyyyMMddHHmmssfff"),
            Path.GetExtension(fileName)
            );
    }
}

I prefer to use:

string result = "myFile_" + DateTime.Now.ToFileTime() + ".txt";

What does ToFileTime() do?

> Converts the value of the current DateTime object to a Windows file time. > > public long ToFileTime() > > A Windows file time is a 64-bit value that represents the number of 100-nanosecond intervals that have elapsed since 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC). Windows uses a file time to record when an application creates, accesses, or writes to a file.

Source: MSDN documentation - DateTime.ToFileTime Method

Perhaps appending DateTime.Now.Ticks instead, is a tiny bit faster since you won't be creating 3 strings and the ticks value will always be unique also.

you can use:

Stopwatch.GetTimestamp();

You can use below instead:

DateTime.Now.Ticks

With the help of the answer from maf-soft I created my own solution, which can handle Pathes too.

So these are the unittests I use:

Assert.Test(new MyPathTools().AppendTimeStamp(@"AnyFile.pdf", new FakeMyDateTime("15.2.2021 15:23:17")), 
											  @"AnyFile20210215152317.pdf");
Assert.Test(new MyPathTools().AppendTimeStamp(@"C:\Temp\Test\", new FakeMyDateTime("15.2.2021 15:23:17")), 
											  @"C:\Temp\Test\20210215152317");
Assert.Test(new MyPathTools().AppendTimeStamp(@"C:\Temp\Test\AnyFile.pdf", new FakeMyDateTime("15.2.2021 15:23:17")), 
											  @"C:\Temp\Test\AnyFile20210215152317.pdf");

The code (for copy&paste) looks like this:

public class MyPathTools 
{
    public string AppendTimeStamp(string fileName)
    {
        return Path.Combine(Path.GetDirectoryName(fileName), string.Concat(Path.GetFileNameWithoutExtension(fileName),
																		   DateTime.Now.ToString("yyyyMMddHHmmss"),
																		   Path.GetExtension(fileName))
            );
    }
}	

The code that works with my Framework (and is unittestable) looks like this:

public class MyPathTools : IMyPathTools
{
    public string AppendTimeStamp(string fileName, IMyDateTime myDateTime)
    {
        return Path.Combine(Path.GetDirectoryName(fileName), string.Concat(Path.GetFileNameWithoutExtension(fileName),
                                                                           myDateTime.Now.ToString("yyyyMMddHHmmss"),
                                                                           Path.GetExtension(fileName))
                );
    }
}