Create a SharePoint Content Type programmatically

Sometimes it is necessary to create a Sharepoint Content Type by code, specially when batch creating content types.  The following code snippet shows how a sharepoint content type can be created in C#.  I have also included some not-so-simple field types like choice and lookup.

 
using (SPSite p_site = new SPSite(urlToSite))
{
    using (SPWeb p_web = p_site.OpenWeb())
    {
        SPContentType CustomContentType = new
                SPContentType(p_web.AvailableContentTypes["ParentContentType"],
                p_web.ContentTypes, "MyContentType");
 
        // A string Field
        p_web.Fields.Add("NumberColumn", SPFieldType.Number);
        SPFieldLink fLink1 = new SPFieldLink(p_web.Fields["NumberColumn"]);
        CustomContentType.FieldLinks.Add(fLink1);
 
        // A required number field
        p_web.Fields.Add("StringColumn", SPFieldType.Text, true);
        SPFieldLink fLink2 = new SPFieldLink(p_web.Fields["StringColumn"]);
        CustomContentType.FieldLinks.Add(fLink2);
 
        //A Choice Field
        p_web.Fields.Add("ChoiceColumn", SPFieldType.Choice, false);
        SPFieldChoice choicefield = (SPFieldChoice)p_web.Fields["ChoiceColumn"];
        
		// Add a group to the filed
        choicefield.Group = "MyGroup";
        
		// Add choices
        choicefield.Choices.Add(string.Empty);
        choicefield.Choices.Add("Yes");
        choicefield.Choices.Add("No");
        
		// Set the default choice
        choicefield.DefaultValue = string.Empty;
        choicefield.Update();
        SPFieldLink fLink3 = new SPFieldLink(choicefield);
        CustomContentType.FieldLinks.Add(fLink3);
 
        p_web.Fields.AddLookup("LookupColumn", new Guid("guidofremotelist"), false); 
             // Edited thanks for Lee Richardson's comment below
        SPFieldLookup lookupfield = (SPFieldLookup)p_web.Fields["LookupColumn"];
        // Set the remote lookup list
        lookupfield.LookupList = new Guid("guidofremotelist"); 
        // Set the remote field
        lookupfield.LookupField = "remotefieldname";
        lookupfield.Update();
        SPFieldLink fLink4 = new SPFieldLink(lookupfield);
        CustomContentType.FieldLinks.Add(fLink4);
        
        p_web.ContentTypes.Add(CustomContentType);
        CustomContentType.Update();
    }
}