Decoding Encoded URL Parameters in C

When working with URL parameters, it's common to encounter encoded strings to prevent special characters from interfering with the data. This article explores how to decode such encoded parameters using C#.

Consider the following URL as an example:

my.aspx?val=/xyz2F

To decode this encoded parameter value, you can utilize the following methods:

Uri.UnescapeDataString()

The Uri.UnescapeDataString(string) method is a straightforward option for decoding URL parameters. It takes the encoded string as input and returns the decoded value.

For instance, to decode the example URL parameter:

string decodedUrl = Uri.UnescapeDataString("my.aspx?val=/xyz2F");

HttpUtility.UrlDecode()

An alternative approach is to use the HttpUtility.UrlDecode(string) method, which also decodes URL parameters effectively.

string decodedUrl = HttpUtility.UrlDecode("my.aspx?val=/xyz2F");

Handling Fully Encoded URLs

It's worth noting that some URL parameters may be fully encoded, meaning they contain multiple layers of encoding. To handle this, you can employ a loop-based approach:

private static string DecodeUrlString(string url) {
    string newUrl;
    while ((newUrl = Uri.UnescapeDataString(url)) != url)
        url = newUrl;
    return newUrl;
}

This approach ensures that even if the URL contains multiple levels of encoding, it will be fully decoded.