Exception: Access violation - file accessing

Question

I try to doing some unit for accessing text files (CSV). I do this:

type
       TCSV_Data = class
       private
         stFile:TextFile;
       public
         constructor Create(path:string);
       end;
.
.
.
constructor TCSV_Data.Create(path: string);
begin
assignfile(stFile,ces);
end;

Problem is, when I call constructor, method assignfile will rise an exception: "Access violation at address 004036FF in module 'myprog.exe'. Write of address 00000010."

When I use a local procedure variable, everything is ok, but I need stFile-handle for accessing this file in other methods.

What can I do with this?

Answer 1

You are probably calling the constructor incorrectly. Almost certainly you are writing:

var
  CsvData: TCSV_Data;
....
CsvData.Create(path);

Such code is not correct. Here is how you do it correctly:

var
  CsvData: TCSV_Data;
....
CsvData := TCSV_Data.Create(path);
try
  // do stuff with CsvData
finally
  CsvData.Free;
end;