Adding source code to the Circle DataBlade® module udr.c file

About this task

You must add code to implement the Contains() function, which you can see in Visual C++ under the Globals node in the Class view. This function implements the same functionality as the rciContains() function in Exercise 4 and the Contains() function in Exercise 5.

Because the Contains() function in the Circle DataBlade® module calls the Distance() function in the Point DataBlade® module, you must include a wrapper function for the Distance() function in the Circle DataBlade® module udr.c file. The Contains() function calls the wrapper function, which loads the Distance() function from the Point DataBlade® module, executes it, and returns the result to the Contains() function.

To implement the Contains() function:

Procedure

Double-click Contains() in the Class view and scroll to the beginning of the udr.c file.

Add the following wrapper function to the udr.c file for the Circle DataBlade® module after the list of #include statements:

mi_double_precision *Distance 
( MI_CONNECTION * Gen_Con, 
Point * Pnt1,  
Point * Pnt2 
) 
{ MI_FUNC_DESC * fd = NULL; 
MI_DATUM ret = NULL; 
mi_integer error = 0;  
fd = mi_routine_get( Gen_Con, 0, "function Distance(Point, Point)"); 
if (fd == NULL)
    DBDK_TRACE_ERROR( "Contains",
            "function Distance(Point, Point) not gotten.", 10 );

ret = mi_routine_exec( Gen_Con, fd, &error, Pnt1, Pnt2); 
if (error != MI_OK)
    DBDK_TRACE_ERROR( "Contains",
         "exec function Distance(Point, Point) failed.", 10 );  
return ret; 
}

Replace the statement Gen_Con = NULL; with the following connection statement:

Gen_Con = mi_open( NULL, NULL, NULL );         
/* Verify that the connection has been established. */         
if( Gen_Con == 0 )         
{                 
         /*
         ** Opening the current connection has failed      
         ** so issue the following message and quit.              
         **         
         **      "Connection has failed in Contains."         
         */        
         DBDK_TRACE_ERROR( "Contains", ERRORMESG1, 10 ); 
    
         /* not reached */         
}

Replace the code between the comment

/* Your_Code
... BEGIN*/

and the comment /*Your_Code ... END*/ with the following code:

/*        
** Computes the distance between        
** the center of the circle and        
** the point.        
*/        
{       
  double * dist = Distance( Gen_Con, Pnt1, &Circ1->center );         
  /* Is the distance within the radius? */         
  if( (*dist - Circ1->radius) <= 0 )         
  {            
        Gen_RetVal = 1;      
  }       
  else       
  {        
        Gen_RetVal = 0;      
  }       
}

Check your source code against the final version of udr.c.
Save the changes to udr.c