Get current user in workflow sharepoint context

/// <summary>
        /// Get current user in workflow sharepoint context
        /// </summary>
        /// <param name="workflowProperties"></param>
        /// <returns></returns>
        public static SPUser GetCurrentUserInWorkflow(Microsoft.SharePoint.Workflow.SPWorkflowActivationProperties workflowProperties)
        {
            string ModifiedbyUserName = Convert.ToString(workflowProperties.Item.GetFormattedValue("Modified By"));
            string[] strChar = { "ID=" };

            string[] strChars = ModifiedbyUserName.Split(strChar, StringSplitOptions.None);

            Int32 iUserID = Convert.ToInt32(strChars[1].Substring(0, strChars[1].IndexOf("\"")));
            
            SPUserCollection usersInSite = workflowProperties.Web.SiteUsers;
            int countUsers = usersInSite.Count;
            for (int iCnt = 0; iCnt <= countUsers - 1; iCnt++)
            {
                if (usersInSite[iCnt].ID == iUserID)
                {
                    return workflowProperties.Web.SiteUsers[iCnt];                    
                }
            }
            return null;
        }