Sitecore Indexing Automation

using Sitecore.ContentSearch;
using Sitecore.ContentSearch.Maintenance;
// add Sitecore.ContentSearch dll in your solution to use above two namespaces

public void Indexing()
{
try
{
   IndexCustodian.FullRebuild(ContentSearchManager.GetIndex("Your_Index_Name"), true);
}
catch (Exception ex)
{
throw ex;
}
}