How to force web, whole list or library to be re-crawled by search in SharePoint 2013 using API

There is a new option in SharePoint 2013 that allows you to reindex list or document library.
You can find more about this on those blogs: 

• http://blogs.msdn.com/b/armenk/archive/2013/02/12/how-to-force-whole-list-or-library-to-be-re-crawled-by-search.aspx 
• http://www.learningsharepoint.com/2012/12/17/the-new-reindex-list-and-reindex-document-library-option-in-sharepoint-2013/

Important: It does not work in SharePoint 2010!

It is also possible to do it for whole web. Thanks to this all items in all lists will be re-crawled.

I would like to show you how to do it using API.
When using API you can use it on any type of list. It also works for non-document library items, like tasks.

Re-crawl Web

void Main()
{
 using (SPSite site = new SPSite("http://demosvr1/web1/"))
 using (SPWeb web = site.OpenWeb())
 {
  object versionObj = web.AllProperties["vti_searchversion"];
  int version = ((versionObj is int) ? ((int) versionObj) : 0); 
  
  web.SetProperty("vti_searchversion", (version + 1));
  web.Update();    
 }
}

Re-crawl list

void Main()
{
 using (SPSite site = new SPSite("http://demosvr1/web1/"))
 using (SPWeb web = site.OpenWeb())
 {    
  SPList docList = web.Lists["Documents"];

  object versionObj = docList.RootFolder.Properties["vti_searchversion"];

  int version = ((versionObj is int) ? ((int) versionObj) : 0); 

   
  docList.RootFolder.SetProperty("vti_searchversion", (version + 1));

  docList.Update();

 }
}