ClientDDERead
int ClientDDERead (unsigned int conversationHandle, char itemName[], unsigned int dataFormat, void *dataBuffer, size_t dataSize, unsigned int timeOut);
Purpose
Allows your program, acting as a DDE client, to request data from the server. The function waits until the data is received or the timeout period expires.
If successful, ClientDDERead returns the number of bytes read. Otherwise, ClientDDERead returns a negative error code.
Parameters
| Input | ||
| Name | Type | Description |
| conversationHandle | unsigned int | The conversation handle that uniquely represents the connection between the server and the client. |
| itemName | char [] | Uniquely identifies the output item; for example, an Excel cell name.
Each server defines its own set of valid item names. The name must be a string of length from 1 to 255. itemName is case insensitive. |
| dataFormat | unsigned int | One of the data formats Microsoft Windows recognizes. Windows supports the following valid data formats: CF_TEXT CF_BITMAP CF_METAFILEPICT CF_SYLK CF_DIF CF_TIFF CF_OEMTEXT CF_DIB CF_PALETTE CF_PENDATA CF_RIFF CF_WAVE CF_OWNERDISPLAY CF_DSPTEXT CF_DSPBITMAP CF_DSPMETAFILEPICT Refer to www.msdn.com for more information about DDE programming and the meaning of each data format type. |
| dataBuffer | void * | The pointer to the buffer in which to receive data. NULL is not allowed unless dataSize is zero. |
| dataSize | size_t | The maximum number of bytes to read. This should be less than or equal to the size of the data buffer. An error is returned if you pass a value greater than INT_MAX. |
| timeOut | unsigned int | The number of milliseconds to wait for a DDE read or write operation to complete. If a value of zero is passed, then a default timeout of 5000 milliseconds is used. |
Return Value
| Name | Type | Description |
| status | int | Return value indicating whether the function was successful. A negative number represents the error code. For functions that read or write data (ClientDDERead, ClientDDEWrite, ServerDDEWrite, AdviseDDEDataReady, BroadcastDDEDataReady), if the function was successful, the return value is the number of bytes transferred. For other DDE Support Library functions, zero represents successful execution. The enumerated type that specifies the absolute values of the error codes is declared in ddesupp.h. For instance, if an invalid parameter is passed, –kDDE_InvalidParameter is returned. Currently, a maximum of 255 concurrent conversations are allowed at any one time. If you exceed this limit, –kDDE_TooManyConversations will be returned. Error codes from –16 to –33 are native DDEML errors, which correspond to Windows DDE error codes starting from 0x4000. |
Additional Information
Library: DDE Support Library
Include file: ddesupp.h
LabWindows/CVI compatibility: LabWindows/CVI 3.0 and later