Access SharePoint online using client object model- Forbidden error

Question

I tried to Create a new list item using client object model. I have created an asp.net application to do the task. It works if I pass the URL of SharePoint server which is installed in my machine. But if I give my SharePoint online URL it is not working as below code shows. I get "The remote server returned an error: (403) Forbidden. " error. Any idea?

ClientContext context = new ClientContext("https://xxx.sharepoint.com/SitePages/");
List announcementsList = context.Web.Lists.GetByTitle("Announcements");
ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();
Microsoft.SharePoint.Client.ListItem newItem = announcementsList.AddItem(itemCreateInfo);
newItem["Title"] = result.City;
newItem["Body"] = result.State;
newItem.Update();
context.ExecuteQuery();

Answer 1

You need to authenticate with your SPO credentials:

var creds = new SharePointOnlineCredentials("[email protected]", password); // Requires SecureString() for password
context.Credentials = creds;

It needs to be done prior to your first context.ExecuteQuery().

Here is info on the SharePointOnlineCredentials class.