Uri.IsBaseOf(Uri) Method in C#

The Uri.IsBaseOf() method in C# is used to determine whether the current Uri instance is a base of the specified Uri instance. This method is particularly useful when working with URL hierarchies and checking if one URI is a parent or base path of another URI.

Syntax

Following is the syntax −

public bool IsBaseOf(Uri uri);

Parameters

uri − The specified Uri instance to test against the current Uri instance.

Return Value

Returns true if the current Uri instance is a base of the specified Uri; otherwise, false.

How It Works

The IsBaseOf() method returns true when:

• The current URI's scheme, host, and port match the target URI

• The current URI's path is a prefix of the target URI's path

• The current URI represents a logical parent or base of the target URI

Using IsBaseOf() with Same Domain URIs

The following example demonstrates how IsBaseOf() works when comparing URIs from the same domain −

using System;

public class Demo {
    public static void Main() {
        Uri baseUri = new Uri("https://www.tutorialspoint.com/");
        Uri childUri = new Uri("https://www.tutorialspoint.com/index.htm");
        
        Console.WriteLine("Base URI: " + baseUri);
        Console.WriteLine("Child URI: " + childUri);
        
        if (baseUri.IsBaseOf(childUri))
            Console.WriteLine("Base URI is the base of Child URI");
        else
            Console.WriteLine("Base URI is not the base of Child URI");
            
        // Test reverse relationship
        if (childUri.IsBaseOf(baseUri))
            Console.WriteLine("Child URI is the base of Base URI");
        else
            Console.WriteLine("Child URI is not the base of Base URI");
    }
}

The output of the above code is −

Base URI: https://www.tutorialspoint.com/
Child URI: https://www.tutorialspoint.com/index.htm
Base URI is the base of Child URI
Child URI is not the base of Base URI

Using IsBaseOf() with Different Domains

The following example shows how IsBaseOf() behaves when comparing URIs from different domains −

using System;

public class Demo {
    public static void Main() {
        Uri uri1 = new Uri("https://www.tutorialspoint.com/csharp/");
        Uri uri2 = new Uri("https://www.example.com/csharp/");
        
        Console.WriteLine("URI 1: " + uri1);
        Console.WriteLine("URI 2: " + uri2);
        
        if (uri1.IsBaseOf(uri2))
            Console.WriteLine("URI 1 is the base of URI 2");
        else
            Console.WriteLine("URI 1 is not the base of URI 2");
            
        // Test with nested paths on same domain
        Uri baseUri = new Uri("https://www.tutorialspoint.com/");
        Uri nestedUri = new Uri("https://www.tutorialspoint.com/csharp/methods.htm");
        
        Console.WriteLine("\nBase URI: " + baseUri);
        Console.WriteLine("Nested URI: " + nestedUri);
        
        if (baseUri.IsBaseOf(nestedUri))
            Console.WriteLine("Base URI is the base of Nested URI");
        else
            Console.WriteLine("Base URI is not the base of Nested URI");
    }
}

The output of the above code is −

URI 1: https://www.tutorialspoint.com/csharp/
URI 2: https://www.example.com/csharp/
URI 1 is not the base of URI 2
Base URI: https://www.tutorialspoint.com/
Nested URI: https://www.tutorialspoint.com/csharp/methods.htm
Base URI is the base of Nested URI

Common Use Cases

The IsBaseOf() method is commonly used in scenarios such as:

• Web scraping − Checking if discovered URLs belong to a specific domain

• Security validation − Ensuring URLs are within allowed base paths

• Relative URL resolution − Determining parent-child relationships between URLs

Conclusion

The Uri.IsBaseOf() method provides an efficient way to determine hierarchical relationships between URIs. It returns true when the current URI represents a logical parent or base path of the specified URI, making it valuable for URL validation and navigation logic.