在delphi中如何保存类型文件？

type
IRecord=record
username:string[50];
password:string[32];
age:integer;
end;
IRecordFile=file of IRecord;
var
rf:IRecordFile;
userinfo:IRecord;
begin
userinfo.username:='bigfoot';
userinfo.password:='password';
userinfo.age:=26;
assignfile(rf,'c:\test.rf')
rewrite(rf);
write(rf,userinfo);
closefile(rf);
end;