error C2065: 'it' : undeclared identifier

Hi

I am migrating my application from vc++6.0 to vc++2008, iam facing this undeclaration error:

before when i was migarting to vc++2013, i was told to use auto key:

for (auto it = m_periods.begin(); it != m_periods.end(); it++)

the error was gone when following this step in vc++2013 but not in vc++2008

below is the list of code:

if (CBalancingPeriod::Includes(m_iAccountingPeriodNo, dCurrent, dReference))
  {
   // Search the reference from the list
   for (it = m_periods.begin(); it != m_periods.end(); it++)
    
   {
    CBalancingPeriod &p = *it;
    if (CBalancingPeriod::Includes(m_iAccountingPeriodNo, p.m_dAccountPeriodStart, dReference))
    {
     return (&p);
    }
   }
  }

========================================================

When using in 2008 the auto keyword, iam getting 2 new errors: " error C2440: 'initializing' : cannot convert from 'std::_List_iterator<std::_List_val<std::_List_simple_types<CBalancingPeriod>>>' to 'int' " 

and  " error C2678: binary '!=' : no operator found which takes a left-hand operand of type 'int' (or there is no acceptable conversion) "

Can anyone telll me the step i need to take to remove this error from vc++2008

Thanks