Question

I have this code:

NameValueCollection nv = HttpUtility.ParseQueryString(queryString);        
foreach (KeyValuePair<String,String> pr in nv) {
    //process KeyValuePair          
}

This compiles, but when I try to run it I get an InvalidCastException.

Why is this? Why can’t I use KeyValuePair to iterate over a NameValueCollection, and what should I use instead?

Answer 1

First of all, NameValueCollection doesn’t use KeyValuePair<String,String>. Also, foreach only exposes the key:

NameValueCollection nv = HttpUtility.ParseQueryString(queryString);        
foreach (string key in nv) {
    var value = nv[key];

}