SharePoint Check user has permission

In this FAQ we will see how to check that a logged in user has access to the site or sub site of the current site using C#.

Many times while working in SharePoint we need to check using code that the current logged in user has access to a particular site or sub site, so that we can avoid the Access Denied error page. So, to do this using C# please refer the below code.

using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using System.Collections.Generic;

namespace WebParts.FacetedNavigationWebPart
{
    [ToolboxItem(false)]
    public partial class FacetedNavigationWebPart : System.Web.UI.WebControls.WebParts.WebPart
    {
        protected override void OnInit(EventArgs e)
        {
             base.OnInit(e);
            InitializeControl();
        }
         
        protected void Page_Load(object sender, EventArgs e)
        {
             if (!Page.IsPostBack)
            {
                SPWeb web = SPContext.Current;
                 string userLoginName = web.CurrentUser.LoginName;
                 if (IsUserHasAccess(web, userLoginName))
                 {
                      lbl.Text = "User has access to " + web.Title;
                 }
                 else {
                     lbl.Text = "User has no access to " + web.Title;
                 }
             }
        }

        private bool IsUserHasAccess(SPWeb web, string userLoginName)
        {
             bool hasAccess = false;
            try
            {
                 web.Site.CatchAccessDeniedException = false;
                hasAccess = web.DoesUserHavePermissions(userLoginName, SPBasePermissions.EmptyMask);
            }
            catch
            {
                hasAccess = false;
            }
            return hasAccess;
        }
     }
}