Question

public static string DictToQueryString(Dictionary<string, string> data)
{
    string querystring = "";

    foreach (string key, string val in data)
         querystring += key + "=" + val + "&";

    return querystring;
}

How i foreach?

Answer 1

Your “code” would have an extraneous "&" on the end. Do you want this? It’s likely that you don’t want this but please correct if you do. Assuming not, the simplest approach is to let String.Join do its job:

public static string DictToQueryString(Dictionary<string, string> data) { 
    return String.Join(
        "&",
        data.Select(kvp => String.Format("{0}={1}", kvp.Key, kvp.Value))
            .ToArray()
    );

In C# 4.0 the call to ToArray will be obviated.