Could someone Reduce this code for me? Its only 4 lines.

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jason p sage

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Posted: 9th Feb 2008 00:09

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I was struggling with this - to get it to work - this code WORKS - but how would you reduce it to TWO lines versus four?

+ Code Snippet

           unsigned int *lpItem1=(unsigned int *)((unsigned int)Item1 + p_lpOffset);
            unsigned int *lpItem2=(unsigned int *)((unsigned int)Item2 + p_lpOffset);
            JFC_STRING_Item1=(JFC_STRING*)*lpItem1;
            JFC_STRING_Item2=(JFC_STRING*)*lpItem2;

Thank you in Advance!

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Todd Riggins

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Posted: 9th Feb 2008 00:28

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assuming variables lpItem1 and lpItem2 are not needed anywhere else.. try converting item + offset to "JFC_STRING*" instead of "unsigned int *" ... like: (ie: a quick quess, dunno if works)

JFC_STRING_Item1=(JFC_STRING*)((unsigned int)Item1 + p_lpOffset);
JFC_STRING_Item2=(JFC_STRING*)((unsigned int)Item2 + p_lpOffset);

may not need (unsigned int) type conversion... try:
JFC_STRING_Item1=(JFC_STRING*)(Item1 + p_lpOffset);
JFC_STRING_Item2=(JFC_STRING*)(Item2 + p_lpOffset);

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jason p sage

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Posted: 9th Feb 2008 01:30 Edited at: 9th Feb 2008 02:49

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I really appreciate the response.

I have tried:

+ Code Snippet

JFC_STRING_Item1=(JFC_STRING*)(Item1 + p_lpOffset);

But unknown to you - Item1 is a (void*) or void pointer.[edit] and the p_lpPointer is an address but is an unsigned int also - the name is misleading[/edit] This means the unsigned int like here is required to compile but gives undesired results:

+ Code Snippet

JFC_STRING_Item1=(JFC_STRING*)((unsigned int)Item1 + p_lpOffset);

So the code snippet I originally posted is the only one that works.

I have a sneaking suspicion I need a ** <----Indirect Pointer notation... but I can't figure out the syntax.

Basically, Item1 - is a pointer to a class, the offset is the position in this pointed to class - of a pointer ... to yet another class.

The code I posted originally - I swear it WORKS, but I'm doing two steps. It took many iterations to get it to work - but it works beautiful I swear. I just think the way I wrote it to finally work still is not "reduced" as much as it could be.

So I'm shooting for:

+ Code Snippet

ADDRESS_IN_MEM + OFFSET = LOCATION_OF_A_POINTER_TO_A_CLASS

Note: ADDRESS_IN_MEM is the value INSIDE the Void* Item1 pointer.

NOTE: TODD - Your answer and my (prior to this post) previous attempts KEPT coming to the syntax you came up with. It seems correct when I read it to. But in the debugger - the only time I see the correct values of this "class" pointed to by a pointer in my Item1 "class" is with the syntax I posted above.

(I was iteratively trying things - 3rd evening trying to fix this flawed code... and I got it today when I came home...)

I think I forced the same functionality as a indirect pointer - or "A pointer that points to a pointer that points to my class" normally described as the ** operator. I dunno - I think I got lucky - I just think Its not as concise as it should be. I also think when someone gets it - somehow seeing the syntax will open a new level of pointer understanding for me (and hopefully others).

Thanx for giving it a honest go of it!
Jason

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Todd Riggins

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Posted: 9th Feb 2008 03:51 Edited at: 9th Feb 2008 03:54

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lol ... i hear exactly what your talking about, ofcoarse I was giving a shot in the dark since I didnt have the rest of your code to look at.

doing stuff like ** is just levels of indirection of pointer management. Like you said, casting a (unsigned int) on a void*(Item1) is needed.

Im "guessing" now that p_lpOffset is a pointer also?? I'll guess Void * for it also for now.

[brain processing]
unsigned int *lpItem1=

(unsigned int *)((unsigned int)Item1 + p_lpOffset);
(unsigned int *)
((unsigned int) ((Void*) + (Void*)) );
casting two pointers into a (unsigned int) result,
once the (unsigned int) result is found,
cast it back to a (unsigned int *).

JFC_STRING_Item1=(JFC_STRING*)*lpItem1;

JFC_STRING_Item1=(JFC_STRING*)*(unsigned int *);
[/brain processing]

Ok, try:
JFC_STRING_Item1=(JFC_STRING*)*((unsigned int *)((unsigned int)Item1 + p_lpOffset));

edit: oh,,, lol I didnt read all of your post clearly... congrats!

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jason p sage

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Posted: 9th Feb 2008 04:11

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haha - Good POST! (Btw - name misleading again - p_lpOffset IS a unsigned int... but the name reflects what I'm trying to use it for - p_ = parameter to my function, lpOffset ... SHOULD mean its a long pointer ... but I meant it as "for pointer math" while I was hacking this together!

(My Bad!)

I like the look of your "Ok Try"! ... Let Me try it!

WOO HOO!!!! YOU DID IT! CONGRATS TO YOU!!!!!!

THANX!

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Todd Riggins

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Posted: 9th Feb 2008 04:20

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lol
I thought wrong at ((unsigned int) ((Void*) + (Void*)) );
I should of known something was fishy with only casting item1 as an unsigned int and not p_lpOffSet. So "assuming" can stear me wrong.

It just came down to plug n' play!

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jason p sage

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Posted: 9th Feb 2008 04:55

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haha... here is the finished code you helped me with:

//-----------------------------------------------------------------------------
bool JFC_DL::SortString(
    bool p_bCaseSensitive,
    unsigned int p_lpOffset,
    bool p_bAscending,
    bool p_bUsePtr,
    bool p_JFC_STRING
){
//-----------------------------------------------------------------------------
  bool bResult;
  void *lpBookMark;
  int i1; 
  int i2;
  int iCompare;
  void *Item1;
  void *Item2;
  JFC_STRING *JFC_STRING_Item1;
  JFC_STRING *JFC_STRING_Item2;
  
  // bubble sort method 
  // Because I didn't know how else to do it for this kind of sort in a double
  // linked list. Other Methods would likely be hindered speed wise because
  // of the way the navigation works. I'm not sure though, but usually fast
  // sorting algorithms work on an array of a set datatype. This is different.
  // This is double linked list that each element is indeed a class, which
  // may contain pointers to other instantiated classes. Its not so bad as is.
  bResult=((!this->IsCopy) && (this->Items>0));
  if(this->Items>1){// Do Actual Sort
    lpBookMark=this->Item; // remember Our Position in list and follow it :)
    // use Ptr, Case Sensitive, Ascending, JFC_STRING
    for(i1=1;i1<=  this->Items ;i1++){
      this->MoveFirst();
      i2=1;
      while(i2<=(Items-1)){
        Item1=this->Item;
        Item2=((JFC_DLITEM*)this->Item)->Next;
        if(p_bUsePtr){
          if(p_JFC_STRING){
            
            // Original Attempt
            //JFC_STRING_Item1=(JFC_STRING*)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset);
            //JFC_STRING_Item2=(JFC_STRING*)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset);

// ORIGINAL WORKING LINES
            //unsigned int *lpItem1=(unsigned int *)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset);
            //JFC_STRING_Item1=(JFC_STRING*)*lpItem1;
            
            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item1=(JFC_STRING*)*((unsigned int *)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset));
            
            // ORIGINAL WORKING LINES
            //unsigned int *lpItem2=(unsigned int *)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset);
            //JFC_STRING_Item2=(JFC_STRING*)*lpItem2;
            
            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item2=(JFC_STRING*)*((unsigned int *)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset));
            
            
            if(p_bCaseSensitive){
              iCompare=strcmp(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            }else{
              iCompare=strcmpi(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            };
          }else{
            if(p_bCaseSensitive){
              iCompare=strcmp(           
                (char*)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset),
                (char*)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset)
              );
            }else{
              iCompare=strcmpi(           
                (char*)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset),
                (char*)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset)
              );
            };  
          };
        }else{
          // NOT using JFC_DLITEM->Ptr
          if(p_JFC_STRING){
            // ORIGINAL WORKING LINES
            //unsigned int *lpItem1=(unsigned int *)((unsigned int)Item1 + p_lpOffset);
            //JFC_STRING_Item1=(JFC_STRING*)*lpItem1;
            
            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item1=(JFC_STRING*)*((unsigned int *)((unsigned int)Item1 + p_lpOffset));
            
            // ORIGINAL WORKING LINES
            //unsigned int *lpItem2=(unsigned int *)((unsigned int)Item2 + p_lpOffset);
            //JFC_STRING_Item2=(JFC_STRING*)*lpItem2;

// CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item2=(JFC_STRING*)*((unsigned int *)((unsigned int)Item2 + p_lpOffset));

if(p_bCaseSensitive){
              iCompare=strcmp(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            }else{
              iCompare=strcmpi(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            };
          }else{
            if(p_bCaseSensitive){
              iCompare=strcmp(           
                (char*)((unsigned int)Item1 + p_lpOffset),
                (char*)((unsigned int)Item1 + p_lpOffset)
              );
            }else{
              iCompare=strcmpi(           
                (char*)((unsigned int)Item1 + p_lpOffset),
                (char*)((unsigned int)Item2 + p_lpOffset)
              );
            };  
          };
        };        
        if(((iCompare>0) && (p_bAscending)) ||
          ((iCompare<0) && (!p_bAscending))){// ascending
          //dbPrint("Swapping items");
          SwapItems(Item1, Item2);
          
          i2+=1;
        };
        this->MoveNext();
        i2+=1;
      };
    };
    this->FoundItem(lpBookMark);
  };
  return bResult;
};
//-----------------------------------------------------------------------------

+ Code Snippet

//-----------------------------------------------------------------------------
bool JFC_DL::SortString(
    bool p_bCaseSensitive,
    unsigned int p_lpOffset,
    bool p_bAscending,
    bool p_bUsePtr,
    bool p_JFC_STRING
){
//-----------------------------------------------------------------------------
  bool bResult;
  void *lpBookMark;
  int i1; 
  int i2;
  int iCompare;
  void *Item1;
  void *Item2;
  JFC_STRING *JFC_STRING_Item1;
  JFC_STRING *JFC_STRING_Item2;
  
  // bubble sort method 
  // Because I didn't know how else to do it for this kind of sort in a double
  // linked list. Other Methods would likely be hindered speed wise because
  // of the way the navigation works. I'm not sure though, but usually fast
  // sorting algorithms work on an array of a set datatype. This is different.
  // This is double linked list that each element is indeed a class, which
  // may contain pointers to other instantiated classes. Its not so bad as is.
  bResult=((!this->IsCopy) && (this->Items>0));
  if(this->Items>1){// Do Actual Sort
    lpBookMark=this->Item; // remember Our Position in list and follow it :)
    // use Ptr, Case Sensitive, Ascending, JFC_STRING
    for(i1=1;i1<=  this->Items ;i1++){
      this->MoveFirst();
      i2=1;
      while(i2<=(Items-1)){
        Item1=this->Item;
        Item2=((JFC_DLITEM*)this->Item)->Next;
        if(p_bUsePtr){
          if(p_JFC_STRING){
            
            // Original Attempt
            //JFC_STRING_Item1=(JFC_STRING*)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset);
            //JFC_STRING_Item2=(JFC_STRING*)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset);

            // ORIGINAL WORKING LINES
            //unsigned int *lpItem1=(unsigned int *)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset);
            //JFC_STRING_Item1=(JFC_STRING*)*lpItem1;
            
            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item1=(JFC_STRING*)*((unsigned int *)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset));
            
            // ORIGINAL WORKING LINES
            //unsigned int *lpItem2=(unsigned int *)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset);
            //JFC_STRING_Item2=(JFC_STRING*)*lpItem2;
            
            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item2=(JFC_STRING*)*((unsigned int *)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset));
            
            
            if(p_bCaseSensitive){
              iCompare=strcmp(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            }else{
              iCompare=strcmpi(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            };
          }else{
            if(p_bCaseSensitive){
              iCompare=strcmp(           
                (char*)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset),
                (char*)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset)
              );
            }else{
              iCompare=strcmpi(           
                (char*)((unsigned int)((JFC_DLITEM*)Item1)->Ptr + p_lpOffset),
                (char*)((unsigned int)((JFC_DLITEM*)Item2)->Ptr + p_lpOffset)
              );
            };  
          };
        }else{
          // NOT using JFC_DLITEM->Ptr
          if(p_JFC_STRING){
            // ORIGINAL WORKING LINES
            //unsigned int *lpItem1=(unsigned int *)((unsigned int)Item1 + p_lpOffset);
            //JFC_STRING_Item1=(JFC_STRING*)*lpItem1;
            
            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item1=(JFC_STRING*)*((unsigned int *)((unsigned int)Item1 + p_lpOffset));
            
            // ORIGINAL WORKING LINES
            //unsigned int *lpItem2=(unsigned int *)((unsigned int)Item2 + p_lpOffset);
            //JFC_STRING_Item2=(JFC_STRING*)*lpItem2;

            // CONSOLIDATED Version (thanx Todd Riggins :) )
            JFC_STRING_Item2=(JFC_STRING*)*((unsigned int *)((unsigned int)Item2 + p_lpOffset));

            
            if(p_bCaseSensitive){
              iCompare=strcmp(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            }else{
              iCompare=strcmpi(JFC_STRING_Item1->s,JFC_STRING_Item2->s);
            };
          }else{
            if(p_bCaseSensitive){
              iCompare=strcmp(           
                (char*)((unsigned int)Item1 + p_lpOffset),
                (char*)((unsigned int)Item1 + p_lpOffset)
              );
            }else{
              iCompare=strcmpi(           
                (char*)((unsigned int)Item1 + p_lpOffset),
                (char*)((unsigned int)Item2 + p_lpOffset)
              );
            };  
          };
        };        
        if(((iCompare>0) && (p_bAscending)) ||
          ((iCompare<0) && (!p_bAscending))){// ascending
          //dbPrint("Swapping items");
          SwapItems(Item1, Item2);
          
          i2+=1;
        };
        this->MoveNext();
        i2+=1;
      };
    };
    this->FoundItem(lpBookMark);
  };
  return bResult;
};
//-----------------------------------------------------------------------------

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