program texttruncate; {$APPTYPE CONSOLE} Uses temps_reel, Windows in 'H:\Borland\Delphi4\Source\Rtl\Win\windows.pas'; Type Testrecord = Record element1 : Integer; element2 : String[10]; End; // record Var thefile : File Of Testrecord; therec : Testrecord; i : LongWord; // Blockread data structures SecondFile : File Of Testrecord; NumRead, NumWritten : Integer; Buffer : array[1..16777216] of Char; Const cNbRec = 1048576; //1048576; // 262143; begin // write test file CountOn; Assign(thefile,'thefile1.dat'); ReWrite(thefile); for i:=0 to cNbRec Do Begin With therec Do Begin element1:=i; element2:='pipo'; End; Write(thefile,therec); End; // for Close(thefile); CountOff; WriteLn('Test File of ',cNbRec,' records (',cNbRec*SizeOf(Testrecord),' bytes) written in ',TimeCount,' seconds.'); // copy into file2 for security because of truncate CopyFile('thefile1.dat','thefile2.dat',False); // direct Win32 API call // truncate CountOn; Assign(SecondFile,'thefile2.dat'); ReSet(SecondFile); Seek(SecondFile,Filesize(SecondFile)-1); Truncate(SecondFile); Close(SecondFile); CountOff; WriteLn('Truncate in ',TimeCount,' seconds.'); // blockread CountOn; Assign(thefile,'thefile1.dat'); ReSet(thefile); Assign(SecondFile,'result1.dat'); ReWrite(SecondFile); (* Seek(thefile,FileSize(thefile)-1); // in records, thus *SizeOf(Testrecord) is useless i:=FilePos(thefile); // in bytes *) // BlockRead(thefile, Buffer, FileSize(thefile)-2, NumRead); // -2 because first element is #0 BlockWrite(SecondFile, Buffer, NumRead, NumWritten); Close(SecondFile); CountOff; WriteLn('BlockWritten in ',TimeCount,' seconds.'); // wait for user ReadLn; end.