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...check, if two files are equal?
Autor: Thomas Stutz
[ Print tip ]  

Tip Rating (5):  
     


{1.}

function Are2FilesEqual(const File1, File2: TFileName): Boolean;
var
  
ms1, ms2: TMemoryStream;
begin
  
Result := False;
  ms1 := TMemoryStream.Create;
  try
    
ms1.LoadFromFile(File1);
    ms2 := TMemoryStream.Create;
    try
      
ms2.LoadFromFile(File2);
      if ms1.Size = ms2.Size then
        
Result := CompareMem(ms1.Memory, ms2.memory, ms1.Size);
    finally
      
ms2.Free;
    end;
  finally
    
ms1.Free;
  end
end
;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if 
Opendialog1.Execute then
    if 
Opendialog2.Execute then
      if 
Are2FilesEqual(Opendialog1.FileName, Opendialog2.FileName) then
        
ShowMessage('Files are equal.');
end;

{********************************************}

{2.}

function FilesAreEqual(const File1, File2: TFileName): Boolean;
const  
  
BlockSize = 65536;
var  
  
fs1, fs2: TFileStream;  
  L1, L2: Integer;  
  B1, B2: array[1..BlockSize] of Byte;
begin  
  
Result := False;  
  fs1 := TFileStream.Create(File1, fmOpenRead or fmShareDenyWrite);
  try    
    
fs2 := TFileStream.Create(File2, fmOpenRead or fmShareDenyWrite);
    try      
      if 
fs1.Size = fs2.Size then 
      begin        
        while 
fs1.Position < fs1.Size do 
        begin          
          
L1 := fs1.Read(B1[1], BlockSize);
          L2 := fs2.Read(B2[1], BlockSize);
          if L1 <> L2 then 
          begin            
            
Exit;
          end;          
          if not CompareMem(@B1[1], @B2[1], L1) then Exit;        
        end;        
        Result := True;      
      end;    
    finally      
      
fs2.Free;    
    end;  
  finally    
    
fs1.Free;  
  end;
end;

 

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