How can you manipulate or modify Query String values programmatically in ASP.NET?

In ASP.NET, you can manipulate or modify query string values programmatically using the 'UriBuilder' class and the 'HttpUtility.ParseQueryString' method. These provide convenient ways to modify query string parameters or create new query strings with updated values.

Here's an example of how you can programmatically manipulate query string values in ASP.NET:

// Get the current URL
UriBuilder uriBuilder = new UriBuilder(Request.Url);

// Parse the query string
var queryStrings = HttpUtility.ParseQueryString(uriBuilder.Query);

// Update an existing query string parameter
queryStrings["id"] = "456";

// Add a new query string parameter
queryStrings["name"] = "Jane";

// Set the modified query string back to the URL
uriBuilder.Query = queryStrings.ToString();

// Get the modified URL
string modifiedUrl = uriBuilder.ToString();

In this example, the 'UriBuilder' class is used to get the current URL, and the 'HttpUtility.ParseQueryString' method is used to parse the query string into a 'NameValueCollection'. You can then modify the values by accessing the individual query string parameters like a dictionary.

In the example, the value of the "id" parameter is updated to "456", and a new parameter "name" is added with the value "Jane". The modified query string is then set back to the 'uriBuilder' object, and the modified URL is obtained using the 'ToString()' method.

By programmatically manipulating query string values, you can dynamically update or modify the parameters based on specific conditions or user input. This allows for flexible customization of URLs and the associated query string parameters in ASP.NET applications.