SharePoint 2013 - Update list items with client object model

Here is a very simple example of using SharePoint Client Object Model. In this example I will update every item in my list, i.e. I will update field "Address" with value "my new value". 

1. Open Visual Studio and go to File --> New Project
2. Select Windows --> Console Application (or SharePoint Console Application)
3. Add Microsoft.SharePoint.Client and Microsoft.SharePoint.Client.Runtime references to your project:

4. Paste this code in you new project:

using Microsoft.SharePoint.Client;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleApplication1 {

    class Program {

        static void Main(string[] args) {

            // Here you need to enter url of your site

            ClientContext ctx = new ClientContext("http://yourSiteUrl");

            // Get the list by its name - here you enter your list title

            List list = ctx.Web.Lists.GetByTitle("ListTitle");

            ListItemCollection coll = list.GetItems(CamlQuery.CreateAllItemsQuery());

            // we need to load all fields

            ctx.Load(coll);

            ctx.ExecuteQuery();

            // change value of one field in every list item

     // NOTE: this field must exist in your list

            foreach (var item in coll) {

                item["Address"] = "my new value";

                item.Update();

                ctx.ExecuteQuery();               

            }

        }

    }

}