NameValueCollection

NameValueCollection is a class in the .NET Framework that represents a collection of keys and values. Each key is a string, and each value can be a single string or an array of strings. This collection is useful for storing and retrieving data where each piece of data has a distinct name.

The NameValueCollection class is derived from the CollectionsUtil class and implements the INameValueCollection interface. It allows for duplicate keys, meaning that multiple values can be associated with the same key. When retrieving values, you can access them by key name or by index. The collection provides methods to add, remove, and check for the existence of keys and values.

One common use case for NameValueCollection is storing query string parameters from a URL. The keys would be the parameter names, and the values would be their corresponding values. It is also frequently used to store HTTP headers or form data.

The class offers flexibility in how values are accessed. You can retrieve a single string value associated with a key, or if there are multiple values for that key, you can retrieve them as a string array. Methods like GetValues and Get are available for this purpose. Iterating through the collection is also straightforward, allowing you to process each key-value pair. When dealing with collections that do not allow duplicate keys, classes like Dictionary<TKey, TValue> might be more appropriate.