Enum pointers in C++

Question

Enum:

    enum DataStatus
    {
        DataNotAvailable = -1,
        DataLocallyAvailable = 0,
        DataExternallyAvailable = 1,
    };

Function definition:

    GetDataStatusByFrame(UINT PI_uiRequestFrameNo, DataStatus *PO_peDataStatus);

Comparsion:

    IDataHandler::DataStatus* pinnedPointer = new IDataHandler::DataStatus();
    GetDataStatusByFrame(1, pinnedPointer);

    if (pinnedPointer == IDataHandler::DataStatus::DataNotAvailable) // 'cannot convert' exception
    {
      // ...
    }

Question:

How can i compare these types or at least cast them to the same datatype?

Maybe you could do with some back to basics information. Consider reading about pointers in your favorite book. — David Rodríguez - dribeas
– David Rodríguez - dribeas, Commented Mar 19, 2012 at 12:15

Joachim Isaksson · Accepted Answer · 2012-03-19 11:40:03Z

4

This API looks like it is intended to be called in a slightly simpler manner to avoid dynamically allocating memory that you need to clean up later. Just put the variable on the stack and it will be cleaned up automatically;

IDataHandler::DataStatus status;

GetDataStatusByFrame(1, &status);

if (status == IDataHandler::DataStatus::DataNotAvailable) // 'cannot convert' exception
{
  // ...
}

answered Mar 19, 2012 at 11:40

Joachim Isaksson

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Comments

Michel Keijzers · Accepted Answer · 2012-03-19 11:33:26Z

3

Use

if (*pinnedPointer == IDataHandler::DataStatus::DataNotAvailable)

answered Mar 19, 2012 at 11:33

Michel Keijzers

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Comments

Griwes · Accepted Answer · 2012-03-19 11:34:01Z

3

if (*pinnedPointer == IDataHandler::DataStatus::DataNotAvailable)
{
    //...
}

answered Mar 19, 2012 at 11:34

Griwes

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Comments

D.Shawley · Accepted Answer · 2012-03-19 11:40:00Z

1

Is the allocation necessary? Why not do the following instead?

IDataHandler::DataStatus status;
GetDataStatusByFrame(1, &status);
if (status == IDataHandler::DataStatus::DataNotAvailable) {
    // ...
}

It is very rare to allocate to an enum pointer. Usually you pass the address of a statically allocated variable.

answered Mar 19, 2012 at 11:40

D.Shawley

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