c:\a\b\c -> c:\a\b\c\d\file.txt = d\file.txt
c:\a\b\c -> c:\a\file.txt = ..\..\file.txt
c:\a\b\c -> c:\a\x\file.txt = ..\..\x\file.txt
I am surprised there is nothing in the .NET framework so I had a hunt around and converted the code from the following URL (http://www.vergentsoftware.com/blogs/ckinsman/default.aspx?date=2006-08-07) into C#....
private string RelativePath(string absolutePath, string relativeTo)
{
string[] absoluteDirectories = absolutePath.Split('\\');
string[] relativeDirectories = relativeTo.Split('\\');
//Get the shortest of the two paths
int length = absoluteDirectories.Length < relativeDirectories.Length ? absoluteDirectories.Length : relativeDirectories.Length;
//Use to determine where in the loop we exited
int lastCommonRoot = -1;
int index;
//Find common root
for (index = 0; index < length; index++)
if (absoluteDirectories[index] == relativeDirectories[index])
lastCommonRoot = index;
else
break;
//If we didn't find a common prefix then throw
if (lastCommonRoot == -1)
throw new ArgumentException("Paths do not have a common base");
//Build up the relative path
StringBuilder relativePath = new StringBuilder();
//Add on the ..
for (index = lastCommonRoot + 1; index < absoluteDirectories.Length; index++)
if (absoluteDirectories[index].Length > 0)
relativePath.Append("..\\");
//Add on the folders
for (index = lastCommonRoot + 1; index < relativeDirectories.Length - 1; index++)
relativePath.Append(relativeDirectories[index] + "\\");
relativePath.Append(relativeDirectories[relativeDirectories.Length - 1]);
return relativePath.ToString();
}
