In my opinion this is a bug. The problem is that there are two different types of "absolute" paths. The path "d:\mydir\myfile.txt" is absolute, the path "\mydir\myfile.txt" is also considered to be "absolute" even though it is missing the drive letter. The correct behavior, in my opinion, would be to prepend the drive letter from the first path when the second path starts with the directory separator (and is not a UNC path). I would recommend writing your own helper wrapper function which has the behavior you desire if you need it.
This is the disassembled code from .NET Reflector for Path.Combine method. Check IsPathRooted function. If the second path is rooted (starts with a DirectorySeparatorChar), return second path as it is.
public static string Combine(string path1, string path2)
{
if ((path1 == null) || (path2 == null))
{
throw new ArgumentNullException((path1 == null) ? "path1" : "path2");
}
CheckInvalidPathChars(path1);
CheckInvalidPathChars(path2);
if (path2.Length == 0)
{
return path1;
}
if (path1.Length == 0)
{
return path2;
}
if (IsPathRooted(path2))
{
return path2;
}
char ch = path1[path1.Length - 1];
if (((ch != DirectorySeparatorChar) &&
(ch != AltDirectorySeparatorChar)) &&
(ch != VolumeSeparatorChar))
{
return (path1 + DirectorySeparatorChar + path2);
}
return (path1 + path2);
}
public static bool IsPathRooted(string path)
{
if (path != null)
{
CheckInvalidPathChars(path);
int length = path.Length;
if (
(
(length >= 1) &&
(
(path[0] == DirectorySeparatorChar) ||
(path[0] == AltDirectorySeparatorChar)
)
)
||
((length >= 2) &&
(path[1] == VolumeSeparatorChar))
)
{
return true;
}
}
return false;
}
Remove the starting slash ('\') in the second parameter (path2) of Path.Combine.
This code should do the trick:
string strFinalPath = string.Empty;
string normalizedFirstPath = Path1.TrimEnd(new char[] { '\\' });
string normalizedSecondPath = Path2.TrimStart(new char[] { '\\' });
strFinalPath = Path.Combine(normalizedFirstPath, normalizedSecondPath);
return strFinalPath;
This actually makes sense, in some way, considering how (relative) paths are treated usually:
string GetFullPath(string path)
{
string baseDir = @"C:\Users\Foo.Bar";
return Path.Combine(baseDir, path);
}
// Get full path for RELATIVE file path
GetFullPath("file.txt"); // = C:\Users\Foo.Bar\file.txt
// Get full path for ROOTED file path
GetFullPath(@"C:\Temp\file.txt"); // = C:\Temp\file.txt
The real question is: Why are paths, which start with "\", considered "rooted"? This was new to me too, but it works that way on Windows:
new FileInfo("\windows"); // FullName = C:\Windows, Exists = True
new FileInfo("windows"); // FullName = C:\Users\Foo.Bar\Windows, Exists = False
Following Christian Graus' advice in his "Things I Hate about Microsoft" blog titled "Path.Combine is essentially useless.", here is my solution:
public static class Pathy
{
public static string Combine(string path1, string path2)
{
if (path1 == null) return path2
else if (path2 == null) return path1
else return path1.Trim().TrimEnd(System.IO.Path.DirectorySeparatorChar)
+ System.IO.Path.DirectorySeparatorChar
+ path2.Trim().TrimStart(System.IO.Path.DirectorySeparatorChar);
}
public static string Combine(string path1, string path2, string path3)
{
return Combine(Combine(path1, path2), path3);
}
}
Some advise that the namespaces should collide, ... I went with Pathy, as a slight, and to avoid namespace collision with System.IO.Path.
Edit: Added null parameter checks
This \ means "the root directory of the current drive". In your example it means the "test" folder in the current drive's root directory. So, this can be equal to "c:\test".
I used aggregate function to force paths combine as below:
public class MyPath
{
public static string ForceCombine(params string[] paths)
{
return paths.Aggregate((x, y) => Path.Combine(x, y.TrimStart('\\')));
}
}
Reason:
Your second URL is considered an absolute path, The Combine method will only return the last path if the last path is an absolute path.
Solution: Just remove the starting slash / of your second Path (/SecondPath to SecondPath). Then it works as you excepted.
These two methods should save you from accidentally joining two strings that both have the delimiter in them.
public static string Combine(string x, string y, char delimiter) {
return $"{ x.TrimEnd(delimiter) }{ delimiter }{ y.TrimStart(delimiter) }";
}
public static string Combine(string[] xs, char delimiter) {
if (xs.Length < 1) return string.Empty;
if (xs.Length == 1) return xs[0];
var x = Combine(xs[0], xs[1], delimiter);
if (xs.Length == 2) return x;
var ys = new List<string>();
ys.Add(x);
ys.AddRange(xs.Skip(2).ToList());
return Combine(ys.ToArray(), delimiter);
}
As mentiond by Ryan it's doing exactly what the documentation says.
From DOS times, current disk, and current path are distinguished.
\ is the root path, but for the CURRENT DISK.
For every "disk" there is a separate "current path".
If you change the disk using cd D: you do not change the current path to D:\, but to: "D:\whatever\was\the\last\path\accessed\on\this\disk"...
So, in windows, a literal @"\x" means: "CURRENTDISK:\x".
Hence Path.Combine(@"C:\x", @"\y") has as second parameter a root path, not a relative, though not in a known disk...
And since it is not known which might be the «current disk», python returns "\\y".
>cd C:
>cd \mydironC\apath
>cd D:
>cd \mydironD\bpath
>cd C:
>cd
>C:\mydironC\apath
I wanted to solve this problem:
string sample1 = "configuration/config.xml";
string sample2 = "/configuration/config.xml";
string sample3 = "\\configuration/config.xml";
string dir1 = "c:\\temp";
string dir2 = "c:\\temp\\";
string dir3 = "c:\\temp/";
string path1 = PathCombine(dir1, sample1);
string path2 = PathCombine(dir1, sample2);
string path3 = PathCombine(dir1, sample3);
string path4 = PathCombine(dir2, sample1);
string path5 = PathCombine(dir2, sample2);
string path6 = PathCombine(dir2, sample3);
string path7 = PathCombine(dir3, sample1);
string path8 = PathCombine(dir3, sample2);
string path9 = PathCombine(dir3, sample3);
Of course, all paths 1-9 should contain an equivalent string in the end. Here is the PathCombine method I came up with:
private string PathCombine(string path1, string path2)
{
if (Path.IsPathRooted(path2))
{
path2 = path2.TrimStart(Path.DirectorySeparatorChar);
path2 = path2.TrimStart(Path.AltDirectorySeparatorChar);
}
return Path.Combine(path1, path2);
}
I also think that it is quite annoying that this string handling has to be done manually, and I'd be interested in the reason behind this.
From MSDN:
If one of the specified paths is a zero-length string, this method returns the other path. If path2 contains an absolute path, this method returns path2.
In your example, path2 is absolute.
If you want to combine both paths without losing any path you can use this:
?Path.Combine(@"C:\test", @"\test".Substring(0, 1) == @"\" ? @"\test".Substring(1, @"\test".Length - 1) : @"\test");
Or with variables:
string Path1 = @"C:\Test";
string Path2 = @"\test";
string FullPath = Path.Combine(Path1, Path2.IsRooted() ? Path2.Substring(1, Path2.Length - 1) : Path2);
Both cases return "C:\test\test".
First, I evaluate if Path2 starts with / and if it is true, return Path2 without the first character. Otherwise, return the full Path2.
Not knowing the actual details, my guess is that it makes an attempt to join like you might join relative URIs. For example:
urljoin('/some/abs/path', '../other') = '/some/abs/other'
This means that when you join a path with a preceding slash, you are actually joining one base to another, in which case the second gets precedence.
Source: Stackoverflow.com