Combine Method (String, String)

Path.Combine Method (String, String)


Combines two strings into a path.

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

public static string Combine(
	string path1,
	string path2


Type: System.String

The first path to combine.

Type: System.String

The second path to combine.

Return Value

Type: System.String

The combined paths. 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.

Exception Condition

path1 or path2 contains one or more of the invalid characters defined in GetInvalidPathChars.


path1 or path2 is null.

If path1 is not a drive reference (that is, "C:" or "D:") and does not end with a valid separator character as defined in DirectorySeparatorChar, AltDirectorySeparatorChar, or VolumeSeparatorChar, DirectorySeparatorChar is appended to path1 before concatenation.

If path2 does not include a root (for example, if path2 does not start with a separator character or a drive specification), the result is a concatenation of the two paths, with an intervening separator character. If path2 includes a root, path2 is returned.

The parameters are not parsed if they have white space. Therefore, if path2 includes white space (for example, " \file.txt "), the Combine method appends path2 to path1 instead of returning only path2.

Not all invalid characters for directory and file names are interpreted as unacceptable by the Combine method, because you can use these characters for search wildcard characters. For example, while Path.Combine("c:\\", "*.txt") might be invalid if you were to create a file from it, it is valid as a search string. It is therefore successfully interpreted by the Combine method.

For a list of common I/O tasks, see Common I/O Tasks.

The following code example demonstrates using the Combine method on a Windows-based desktop platform.

using System;
using System.IO;

public class ChangeExtensionTest {

    public static void Main() {

        string path1 = "c:\\temp";
        string path2 = "subdir\\file.txt";
        string path3 = "c:\\temp.txt";
        string path4 = "c:^*&)(_=@#'\\^&#2.*(.txt";
        string path5 = "";
        string path6 = null;

        CombinePaths(path1, path2);
        CombinePaths(path1, path3);
        CombinePaths(path3, path2);
        CombinePaths(path4, path2);
        CombinePaths(path5, path2);
        CombinePaths(path6, path2);

    private static void CombinePaths(string p1, string p2) {

        try {
            string combination = Path.Combine(p1, p2);

            Console.WriteLine("When you combine '{0}' and '{1}', the result is: {2}'{3}'",
                        p1, p2, Environment.NewLine, combination);
        } catch (Exception e) {
            if (p1 == null)
                p1 = "null";
            if (p2 == null)
                p2 = "null";
            Console.WriteLine("You cannot combine '{0}' and '{1}' because: {2}{3}",
                        p1, p2, Environment.NewLine, e.Message);

// This code produces output similar to the following:
// When you combine 'c:\temp' and 'subdir\file.txt', the result is: 
// 'c:\temp\subdir\file.txt'
// When you combine 'c:\temp' and 'c:\temp.txt', the result is: 
// 'c:\temp.txt'
// When you combine 'c:\temp.txt' and 'subdir\file.txt', the result is: 
// 'c:\temp.txt\subdir\file.txt'
// When you combine 'c:^*&)(_=@#'\^&#2.*(.txt' and 'subdir\file.txt', the result is: 
// 'c:^*&)(_=@#'\^&#2.*(.txt\subdir\file.txt'
// When you combine '' and 'subdir\file.txt', the result is: 
// 'subdir\file.txt'
// You cannot combine '' and 'subdir\file.txt' because: 
// Value cannot be null.
// Parameter name: path1

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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