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Posted: **Mon Jul 29, 2019 9:08 am**

Can the compareMemory() return value be modyfied so that when comparing memory areas the return value is 0 when they are the same and the byte number beginning at 1 of the first byte that does not match?

Maybe just use this:-

Code: Select all

Procedure.l CompareMemoryByte(*Mem1,Mem2,Length.l)
  
  Define Pointer.l

  
  For Pointer = 0 To Length
    If PeekA(*mem1 + Pointer) <> PeekA(*mem1 + Pointer)
      ProcedureReturn Pointer
    EndIf
    ProcedureReturn -1
    
  EndProcedure

CD

Posted: **Mon Jul 29, 2019 9:18 am**

So you need FindString() but for binary data?
Unfortunality there is no such command available but you could try to implement your own or search in the board for a similar approach. I remember seeing such a procedure in the past. Maybe an other member knows where it is.

Posted: **Mon Jul 29, 2019 9:25 am**

Wilbert's Module FindData

viewtopic.php?f=12&t=62519

Posted: **Mon Jul 29, 2019 9:32 am**

collectordave wrote:Can the compareMemory() return value be modyfied so that when comparing memory areas the return value is 0 when they are the same and the byte number beginning at 1 of the first byte that does not match?

That's not a good idea, because it would break existing code. What you need is another function.

idle was quicker ...
Anyway, in cases like this it's always a good idea to search the forum for "wilbert".

Or perhaps a simple function like the following might be sufficient:

Code: Select all

Procedure.i MemoryDiff (*mem1.Byte, *mem2.Byte, size.i)
   ; -- simple byte by byte comparison of two memory areas
   ; in : *mem1, *mem2: pointers to the memory areas
   ;      size        : number of bytes to compare
   ; out: offset where the first difference is, or
   ;      -1 if both areas are identical or
   ;      -2 on error
   Protected offset.i, last.i=size-1
   
   If *mem1 = 0 Or *mem2 = 0 Or size < 0
      ProcedureReturn -2
   ElseIf *mem1 = *mem2
      ProcedureReturn -1
   EndIf
   
   For offset = 0 To last
      If *mem1\b <> *mem2\b
         ProcedureReturn offset
      EndIf
      *mem1 + 1
      *mem2 + 1
   Next
   
   ProcedureReturn -1
EndProcedure

Posted: **Mon Jul 29, 2019 10:03 am**

Updated first post with little procedure to do it.

Thanks for all your replies.

regards

CD

Posted: **Mon Jul 29, 2019 8:12 pm**

First make sense with a huge amount of data.

Move to General Discussion
Link: viewtopic.php?f=7&t=73297

Code: Select all

... Move

Posted: **Tue Jul 30, 2019 3:40 am**

Nice one.

Just what I needed.

CD

Posted: **Tue Jul 30, 2019 4:14 am**

With large data it will be faster to test long integers instead of bytes, then just do bounds testing and find within the failed integer to find the byte.

PureBasic Forums - English

Comparememory() return Value [Done]

Comparememory() return Value [Done]

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