/*****************************************************************************************************************

SAS file name: tips_hash_object
File location: 
_________________________________________________________________________________________________________________

Purpose: To present five tips to learn and understand the hash object in SAS
Author: Peter Clemmensen
Creation Date: 18/01/2019

This program supports the example page "5 Tips to Learn and Understand the Hash Object in SAS" on SASnrd.com

*****************************************************************************************************************/

/* 1. Read the proper literature */

/* 2. The PDV and Host Variable Interaction */

data _null_;
   declare hash h();
   h.defineKey('k');
   h.defineData('d');
   h.defineDone();

   k=1;d=2;
   h.add();         /* PDV --> Hash Object */
   k=2;d=4;
   h.add();         /* PDV --> Hash Object */

   k=1;
   rc=h.find();     /* HAsh Object --> PDV */

   put k= +2 d=;
run;

/* 3. The Hash Function */
data _null_;
   do i=1 to 50;
      string="Hash This!";
      one=md5(string);
      two=sha256(string);
      put one hex32. / two hex32.;
   end;
run;

/* 4. An In-Memory Structure */

/* 5. The Ability to Grow and Shrink at Run Time */
data _null_;
   declare hash h();
   h.defineKey('k');
   h.defineData('d');
   h.defineDone();

   do k=1 to 10;
      d=k*2;
      h.add();
      num=h.num_items;
      put num=;
   end;
   do k=10 to 1 by -1;
      h.remove();
      num=h.num_items;
      put num=;
   end;
run;