jtoddcs jtoddcs - 1 month ago 18
C# Question

Finding a unique File ID, based on path, in C#

I need a way to determine if a user has copied a file to a new location.

Example: You have two computers and you copy file.txt from C:\Temp\ on computer1 to C:\Temp\ on computer2.

Is there an ID associated with these two files, based on their location, that will help me determine if this file has moved?

Update: After some discussion, here is the resulting code. This determines if a file has been copied by creating a Guid using the file path and creation time. This resulting Guid can be compared to a stored Guid to determine if the file has been copied.

FileInfo fi = new FileInfo("C:\\Temp\\temp.txt");
string filePathCreationComposite = String.Format("{0}{1}", Path.GetFullPath(fi.FullName), fi.CreationTime);

using (MD5 md5 = MD5.Create())
{
byte[] hash = md5.ComputeHash(Encoding.Default.GetBytes(filePathCreationCo‌​mposite));
Guid result = new Guid(hash);
}

Answer

You should be able to check either the creation time or last write time with the System.IO.FileInfo class. That, along with path information should be enough to tell you whether a file has changed or moved.

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