How to add items to a collection while consuming it?

Question

The example below throws an InvalidOperationException, \"Collection was modified; enumeration operation may not execute.\" when executing the code.

var urls         


        

Answer 1

alternately, you could treat the collection as a queue

IList urls = new List();
urls.Add("http://www.google.com");
while (urls.Count > 0)
{
    string url = urls[0];
    urls.RemoveAt(0);
    // Get all links from the url
    List newUrls = GetLinks(url);
    urls.AddRange(newUrls);
}