C# Iterate through NameValueCollection

Question

I have a NameValueCollection, and want to iterate through the values. Currently, I’m doing this, but it seems like there should be a neater way to do it:

NameValueCollection nvc = new NameValueCollection(); nvc.Add("Test", "Val1"); nvc.Add("Test2", "Val1"); nvc.Add("Test2", "Val1"); nvc.Add("Test2", "Val2"); nvc.Add("Test3", "Val1"); nvc.Add("Test4", "Val4");  foreach (string s in nvc)     foreach (string v in nvc.GetValues(s))         Console.WriteLine("{0} {1}", s, v);  Console.ReadLine(); 

Is there?

Answer 1

You can use the key for lookup instead of having two loops:

foreach (string key in nvc) {     Console.WriteLine("{0} {1}", key, nvc[key]); } 

Answer 2

You can flatten the collection with Linq, but it's still a foreach loop but now more implicit.

var items = nvc.AllKeys.SelectMany(nvc.GetValues, (k, v) => new {key = k, value = v}); foreach (var item in items)     Console.WriteLine("{0} {1}", item.key, item.value); 

The first line, converts the nested collection to a (non-nested) collection of anonymous objects with the properties key and value.

It's flatten in the way that it's now a mapping key -> value instead of key -> collection of values. The example data:

Before:

Test -> [Val],

Test2 -> [Val1, Val1, Val2],

Test3 -> [Val1],

Test4 -> [Val4]

After:

Test -> Val,

Test2 -> Val1,

Test2 -> Val1,

Test2 -> Val2,

Test3 -> Val1,

Test4 -> Val4