DH_AppendString
DH_AppendString — appends a string to a point.
Syntax
#include <cogent.h>
ST_STATUS DH_AppendString( | IP_Task* | myself, |
| | PT_pCPOINT | ppoint, |
| | char* | str, |
| | IP_Msg* | hmsg, |
| | ER_hLIST | elist); |
Arguments
- myself
- The
task handle associated with this task. This should always be
the return value from IP_NserveInit.
- ppoint
- A
pointer to a Cascade DataHub point structure. All fields are valid,
and will be treated by the write, but in the first call on a
point the address field must be zero. It will be filled in
automatically. This address will be valid so long as the point
exists in the DataHub, and if, in subsequent
DH_* functions, the address is provided
for this point, the function will run slightly faster.
- str
- The
string of characters to be appended to the existing point
value.
- hmsg
- A
handle to a previously allocated message structure (using IP_MsgCreate) providing enough
buffer space to handle the inter-process communication
associated with the DataHub transaction.
- elist
- A
return value containing error information. This is unimplemented in this
version, and should be NULL.
Returns
ST_OK on
success, ST_ERROR on failure, or some other
value of ST_STATUS.
Description
This function appends a string to
the value of a point. It is an atomic function that operates in
one step, without reading or evaluating the existing value of the
point. This provides a way to modify the value quickly, without
interference or serialization problems.
