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ReuseDDElParam function

Applies to: desktop apps only

Enables an application to reuse a packed Dynamic Data Exchange (DDE) lParam parameter, rather than allocating a new packed lParam. Using this function reduces reallocations for applications that pass packed DDE messages.

Syntax

Copy

LPARAM WINAPI ReuseDDElParam(
  __in  LPARAM lParam,
  __in  UINT msgIn,
  __in  UINT msgOut,
  __in  UINT_PTR uiLo,
  __in  UINT_PTR uiHi
);

Parameters

lParam [in]

Type: LPARAM

The lParam parameter of the posted DDE message being reused.

msgIn [in]

Type: UINT

The identifier of the received DDE message.

msgOut [in]

Type: UINT

The identifier of the DDE message to be posted. The DDE message will reuse the packed lParam parameter.

uiLo [in]

Type: UINT_PTR

The value to be packed into the low-order word of the reused lParam parameter.

uiHi [in]

Type: UINT_PTR

The value to be packed into the high-order word of the reused lParam parameter.

Return value

Type: LPARAM

The return value is the new lParam value.

Remarks

The return value must be posted as the lParam parameter of a DDE message; it must not be used for any other purpose. Once the return value is posted, the posting application need not perform any action to dispose of the lParam parameter.

Use ReuseDDElParam instead of FreeDDElParam if the lParam parameter will be reused in a responding message. ReuseDDElParam returns the lParam appropriate for reuse.

This function allocates or frees lParam parameters as needed, depending on the packing requirements of the incoming and outgoing messages. This reduces reallocations in passing DDE messages.

Requirements