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The routine CPXsetnetcallbackfunc is used to set the
 user-written callback routine to be called each time a log message is issued
 during the optimization of a network program. If the display log is turned
 off, the callback routine will still be called.
This routine works in the same way as the routine
 CPXsetlpcallbackfunc. It enables the user to create a
 separate callback function to be called during the solution of a network
 problem. The prototype for the callback function is identical to that of
 CPXsetlpcallbackfunc.
Callback description
 int callback (CPXCENVptr env,
               void       *cbdata,
               int        wherefrom,
               void       *cbhandle);
 This is the user-written callback routine.
Callback return value
A nonzero terminates the optimization.
Callback arguments
env
A pointer to the CPLEX environment that was passed into the associated optimization routine.
cbdata
A pointer passed from the optimization routine to the user-written
 callback function that identifies the problem being optimized. The only
 purpose for the cbdata pointer is to pass it to the routine
 CPXgetcallbackinfo.
wherefrom
An integer value indicating from which optimization algorithm the user-written callback function was called. Possible values and their meaning appear in the table.
| Value | Symbolic Constant | Meaning | 
3 | CPX_CALLBACK_NETWORK | From network simplex | 
cbhandle
Pointer to user private data, as passed to
 CPXsetnetcallbackfunc.
Parameters
env
A pointer to the CPLEX environment as returned by CPXopenCPLEX.
callback
A pointer to a user-written callback function. 
 Setting callback to NULL prevents any 
 callback function from being called during optimization. 
 The call to callback occurs after every log message is issued  
 during optimization and periodically during the CPLEX presolve algorithms. 
 This function is written by the user. 
cbhandle
A pointer to user private data. This pointer is passed to the callback function.
Example
status = CPXsetnetcallbackfunc (env, myfunc, NULL);
See Also:
CPXgetcallbackinfo, CPXsetlpcallbackfunc, CPXsetmipcallbackfunc