RE: bsearch on partial array elements

[Alan Campin <Alan.Campin@xxxxxxxxxxxxx>]

Here is an example of how I would think you would do it. 

Original code. 

 p CompareProc     b                                       
 d                 pi                  like(StdBin)        
 d  ptrLookFor                         like(StdPtr)        
 d                                       value             
 d  ptrArrayElem                       like(StdPtr)        
 d                                       value             
                                                           
 d wfKey           s                   like(StdNam)        
 d                                     based(ptrLookFor)   
 d wfArrElt        s                   like(StdNam)        
 d                                     based(ptrArrayElem) 
                                                           
 d cLessThan       c                   const(-1)           
 d cGreaterThan    c                   const(1)            
 d cEqualTo        c                   const(0)            
                                                           
 c                   select                                
 c                   when      wfKey < wfArrElt          
 c                   return    cLessThan                 
 c                   when      wfKey = wfArrElt          
 c                   return    cEqualTo                  
 c                   when      wfKey > wfArrElt          
 c                   return    cGreaterThan              
 c                   endsl                               
 p CompareProc     e
                                     
Code modified to check a short key.
 
 p CompareProc     b                                             
 d                 pi                  like(StdBin)              
 d  ptrLookFor                         like(StdPtr)              
 d                                       value                   
 d  ptrArrayElem                       like(StdPtr)              
 d                                       value                   
                                                                 
 d wfKey           s                   like(StdNam)              
 d                                     based(ptrLookFor)         
 d wfArrElt        s                   like(StdNam)              
 d                                     based(ptrArrayElem)       
                                                                 
 d cLessThan       c                   const(-1)                 
 d cGreaterThan    c                   const(1)                  
 d cEqualTo        c                   const(0)                  
 d ShortElem       s              5
 d ShortKey        s              5

 c                   eval       SortElement = %substr(wfArrElt:1:5)

 c                   eval       SortKey     = %substr(wfKey:1:5)           
 c                   select                                      
 c                   when      SortKey < ShortElem           
 c                   return    cLessThan                  
 c                   when      SortKey = ShortElem           
 c                   return    cEqualTo                   
 c                   when      SortKey > ShortElem           
 c                   return    cGreaterThan               
 c                   endsl                                
 p CompareProc     e                                      

-----Original Message-----
From: David.Biggs@bernardmatthews.com
[mailto:David.Biggs@bernardmatthews.com]
Sent: Thursday, January 13, 2000 8:45 AM
To: rpg400-l@midrange.com
Subject: bsearch on partial array elements




I have an RPG IV program in which I am using 'bsearch' to search a number of
arrays, which is working fine (and quickly too !). However, one of the
arrays is
defined with an element length of 37A, but I want to search it by the first
30
bytes only.
The trailing 7 bytes of the array elements will not contain blanks, so I
assume
that the bsearch routine will not work correctly when comparing 30A to 37A.

Any ideas how I can get round this without creating more arrays ?

TIA,
Dave Biggs





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