Error when using FileSize(F) in Delphi 2010

Question

I'm writing an application to log microscope usage but the following piece of code generates an error E2010 incompatible types "WideString' and "TDataFile" at the line that reads: SetLength(Items, FileSize(F)); I have narrowed down the problem to FileSize(F), just a number instead gives no error and trying to assign i := fileSize(F); where i is an integer gives the same error.

type
  TData = record
    Status : integer; // 0=operational 1=maintenance 2=fault
    OperatorName : string[255];
    Client : string[255];
    Specimen : string[255];
    Memo : string[255];
    TEM : TTEM;
    SEM : TSEM;
    FIB : TFIB;
    StartTime : string[22]; // YYYY/MM/DD HH:MM:SS AM
    FinishTime : string[22];
    DataFileName : string[255];
  end;

  TDataFile = File of TData;

  TDataArray = array of TData

function LoadAllData(FileName: string; var Items: TDataArray):boolean;
// Loads contents of Datafile into Items and returns true if successful else false
var
  F : TDataFile;
  i : integer;
begin
  AssignFile(F, FileName);
  try
    try
      Reset(F);
      SetLength(Items, FileSize(F)); // This is the problem line
      for i := 0 to High(Items) do
        Read(F, Items[i]);
      LoadAllData := true;
    except
      LoadAllData := false;
    end;
  finally
    CloseFile(F);
  end;
end;

I'm using delphi 2010 on Win7 64bit. Does anyone know why this is happening? Writing a small console app just to test i := FileSize(F); works without a problem....

Answer 1

It seems that you have a function called FileSize declared in another unit or part of your code, something like

function FileSize(const f : WideString):integer;
begin

//

end;

to resolve the issue, add the unit name of the function (in this case System ) before the function name to explicitly call the FileSize function.

SetLength(Items, System.FileSize(F));