Empty string in Delphi / Windows combo box causes access exception -

i've got delphi 7.0 application throws memory access exception / message box every time writeln's empty string string list associated combo box:

csvstrlst := combobox1.items;  csvstrlst.clear; csvstrlst.add('');    //problem csvstrlst.add('a');   //no problem csvstrlst.add('');    //problem csvstrlst.add('b');   //no problem  //throws memory access messages (i think writeln writes line though) n := 1 csvstrlst.count begin     writeln(out_file,csvstrlst.strings[n-1]) end;  //throws memory access messages (writeln write comma text string though) writeln(out_file,csvstrlst.commatext); 

running on windows 7 or xp. application or in d7 ide. combobox empty string items causes same error if parent of form on changed.

has else ever seen or heard of problem? other information available @ all?

this known , solved bug described in qc:

tcombobox gives av when selecting empty item dropdown

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although bug, should not reuse parts controls perform data tasks described in question.

you not save doing so, getting time unwanted sideeffects (controls repainted and/or fire events)

if want have tstringlist create instance.

csvstrlst := tstringlist.create; try    // csvstrlst.clear;   csvstrlst.add( '' );   csvstrlst.add( 'a' );   csvstrlst.add( '' );   csvstrlst.add( 'b' );    n := 0 csvstrlst.count - 1    begin     writeln( out_file, csvstrlst[n] )   end;    writeln( out_file, csvstrlst.commatext );    csvstrlst.free; end;