Check if Key Exists in NameValueCollection

c# .net namevaluecollection
Muhammad Yussuf picture Muhammad Yussuf · Mar 26, 2012 · Viewed 103.6k times · Source

Is there a quick and simple way to check if a key exists in a NameValueCollection without looping through it?

Looking for something like Dictionary.ContainsKey() or similar.

There are many ways to solve this of course. Just wondering if someone can help scratch my brain itch.

Answer

abatishchev picture abatishchev · Mar 26, 2012

From MSDN:

This property returns null in the following cases:

1) if the specified key is not found;

So you can just:

NameValueCollection collection = ...
string value = collection[key];
if (value == null) // key doesn't exist

2) if the specified key is found and its associated value is null.

collection[key] calls base.Get() then base.FindEntry() which internally uses Hashtable with performance O(1).

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