XPRSaddcbmessage
XPRSaddcbmessage |
Purpose
Declares an output
callback function, called every time a text line relating to the given XPRSprob is output by the Optimizer. This callback function will be called in addition to any callbacks already added by XPRSaddcbmessage.
Synopsis
int XPRS_CC XPRSaddcbmessage(XPRSprob prob, void (XPRS_CC *f_message)(XPRSprob my_prob, void *my_object, const char *msg, int len, int msgtype), void *object, int priority);
Arguments
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prob
|
The current problem.
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f_message
|
The callback function which takes five arguments,
my_prob,
my_object,
msg,
len and
msgtype, and has no return value. Use a
NULL value to cancel a callback function.
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my_prob
|
The problem passed to the callback function.
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my_object
|
The user-defined object passed as
object when setting up the callback with
XPRSaddcbmessage.
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msg
|
A null terminated character array (string) containing the message, which may simply be a new line.
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len
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The length of the message string, excluding the null terminator.
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msgtype
|
Indicates the type of output message:
A negative value indicates that the Optimizer is about to finish and the buffers should be flushed at this time if the output is being redirected to a file.
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object
|
A user-defined object to be passed to the callback function.
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priority
|
An integer that determines the order in which callbacks of this type will be invoked. The callback added with a higher priority will be called before a callback with a lower priority. Set to 0 if not required.
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Related controls
Integer
|
All messages are disabled if set to zero.
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Example
The following example simply sends all output to the screen (
stdout):
XPRSaddcbmessage(prob,Message,NULL,0);
The callback function might resemble:
void XPRS_CC Message(XPRSprob my_prob, void* object,
const char *msg, int len, int msgtype)
{
switch(msgtype)
{
case 4: /* error */
case 3: /* warning */
case 2: /* not used */
case 1: /* information */
printf("%s\n", msg);
break;
default: /* exiting - buffers need flushing */
fflush(stdout);
break;
}
}
Further information
1. Screen output is automatically created by the Optimizer Console only. To produce output when using the Optimizer library, it is necessary to define this callback function and use it to print the messages to the screen (
stdout).
2. This function offers one method of handling the messages which describe any warnings and
errors that may occur during execution. Other methods are to check the return values of functions and then get the error code using the
ERRORCODE attribute, obtain the last error message directly using
XPRSgetlasterror, or send messages direct to a log file using
XPRSsetlogfile.
3. Visual Basic users must use the alternative function
XPRSaddcbmessageVB
to define the callback; this is required because of the different way VB handles strings.
Related topics