var
NeedStr : TStringList;
begin
NeedStr := TStringList.Create;
.....
try
......
tinally
needstr.free; /// 如果needstr值为nil时,直接释放会产生 invalid pointer operation 错误提示.
//应该改为: if NeedStr.Count>0 then NeedStr.Free;
end;
delphi TStringList.free 释放错误 invalid pointer operation
原文：http://www.cnblogs.com/smartlittleant/p/4081879.html