Default.aspx.cs

using Microsoft.SharePoint.Client;
using System;
using System.Text;
using System.Web;

namespace BlogNoneSpFullPageWeb
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            var search = HttpUtility.ParseQueryString(Request.Url.Query).Get("search");
            var hostUrl = HttpUtility.ParseQueryString(Request.Url.Query).Get("SPHostUrl");
            Uri spHostUrl = new Uri(hostUrl);
            
            using (var clientContext = TokenHelper.GetS2SClientContextWithWindowsIdentity(spHostUrl, Request.LogonUserIdentity))
            {
                List spList = clientContext.Web.Lists.GetByTitle("Custom List");
                StringBuilder buildQuery = new StringBuilder();
                buildQuery.Append("<View><Query><Where><Contains>");
                buildQuery.Append("<FieldRef Name='Title' /><Value Type='Text'>");
                buildQuery.Append(search);
                buildQuery.Append("</Value></Contains></Where></Query></View>");

                CamlQuery camlQuery = new CamlQuery();
                camlQuery.ViewXml =buildQuery.ToString();

                ListItemCollection listItems = spList.GetItems(camlQuery);
                clientContext.Load(listItems);
                clientContext.ExecuteQuery();

                foreach (var item in listItems)
                {
                    Result.Text += item["Title"].ToString() + "<br/>";
                }
            }
        }
    }
}