Add search condition on Kentico smart search API

Below is an example of using the Smart Search API module in Kentico.

The API Example inside Kentico not telling this, but I was able to figure out the way. 

Kindly have a try on the snippet example 

Smart Search Module API - Search With Condition 

   public void SmartSearchWithCondition(string searchText,string ClassName,string extraCondition)  
   {       
     DocumentSearchCondition docCondition = new DocumentSearchCondition();  
     docCondition.ClassNames = ClassName;  
     docCondition.Culture = "en-US";  
     //refer https://docs.kentico.com/display/K82/Smart+search+syntax for the extra condition syntax  
     var condition = new SearchCondition(extraCondition, SearchModeEnum.AllWords, SearchOptionsEnum.FullSearch, docCondition, true);  
     searchText = SearchSyntaxHelper.CombineSearchCondition(searchText, condition);  
      // Get the search index  
     SearchIndexInfo index = SearchIndexInfoProvider.GetSearchIndexInfo("SearchIndex");  
     if (index != null)  
     {  
       // Prepare parameters  
       SearchParameters parameters = new SearchParameters()  
       {  
         SearchFor = searchText,  
         SearchSort = "##SCORE##",  
         CurrentCulture = "EN-US",  
         DefaultCulture = CultureHelper.EnglishCulture.IetfLanguageTag,  
         CombineWithDefaultCulture = false,  
         CheckPermissions = false,  
         SearchInAttachments = false,  
         User = (UserInfo)MembershipContext.AuthenticatedUser,  
         SearchIndexes = index.IndexName,  
         StartingPosition = 0,  
         AttachmentWhere = String.Empty,  
         AttachmentOrderBy = String.Empty,  
       };  
       // Search  
       DataSet results = SearchHelper.Search(parameters);  
       // If found at least one item  
       if (parameters.NumberOfResults > 0)  
       {  
         //do your works here  
       }  
     }  
   }  

Have a try!