How to iterate through keys and values of an `IDictionary`?
How would I iterate through the keys and values of an IDictionary if I don't know the concrete types of the keys and values within, therefore want to just treat them as object s?
If I do something like:
foreach(var x in myIDictionary) { ... }
I think x is an object . But how would I get the Key and Value out of it (both typed as object s), as specified in the IDictionaryEnumerator ? There isn't an IKeyValuePair without generic parameters is there?
I guess I could loop through the enumerator by hand using MoveNext etc, but I feel like there must be a way to do it with foreach !
You can explicitly specify DictionaryEntry pair type in foreach like this:
foreach (DictionaryEntry x in myIDictionary)
Though you should be sure that it is standard implementation of IDictionary (like Hashtable or Dictionary<TKey, TValue> )
Otherwise it can be literally anything in enumerator.
The point you're missing is that there are no guarantees of what the type of the values will be if you iterate an IDictionary . They could be literally anything. The only guarantee is that it implements .GetEnumerator() .
If you want to iterate over the contents of the IDictionary , you can iterate over its keys:
foreach (object key in myIDictionary.Keys)
{
object value = myIDictionary[key];
// do something with key and value
}
You can also convert your IDictionary to a Dictionary<object, object> to make foreach a bit more friendly:
var myDictionary = myIDictionary.Keys
.Cast<object>()
.ToDictionary(k => k, k => d[k]);
// kv is a KeyValuePair<object, object>
foreach (var kv in dobj)
{
}
You can even add an extension method to do this for you:
public static Dictionary<object, object> ToDictionary(this IDictionary dict)
{
return dict.Keys.Cast<object>().ToDictionary(k => k, k => dict[k]);
}
// usage
// kv is a KeyValuePair<object, object>
foreach (var kv in myIDictionary.ToDictionary())
{
}