Date: Sat, 21 Jun 1997 15:27:31 -0700 (PDT)
Message-Id: <199706212227.PAA05972@geocities.com>
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To: djgpp AT delorie DOT com
From: Guilherme Silveira <thedarkage AT mail DOT geocities DOT com>
Subject: RE: Callbacks
Precedence: bulk

Please, can you give me an example with a function that returns an int and
got 2 parameters, one array of chars (70 chars) and one integer?

At 11:26 18/06/1997 +0100, you wrote:
>>
>>Goretec3 (goretec3 AT aol DOT com) writes:
>>> What are interrupt calbacks. I saw one when I was looking through some
>>> allegro code. 
>>
>>Unless you are a wizard or some kind of guru... you don't want to know. ;-)
>
>Sorry, but if thats your attitude then you are missing out on a
>particularly effective method of
>calling routines...
>
>In C it is possible to have pointers not only to data, but to functions
>as well, these are the pointers that are passed to interrupt handling
>routines in Allegro and other such API's.  It works that when an
>interrupt is processed, the function, which you registered the pointer
>for is called.
>
>You do not have to have these only for Interrupts, they are particularly
>effective for state transition when you want to program objectively in
>C....
>
>/*	StateTransitions.c		*/
>#include <stdlib.h>
>#include <stdio.h>
>
>/* were gonna model a fish object */
>typedef int ( *FISH_STATE )( );
>
>/* now we define the possible states */
>int fishSwimming();
>int fishEating();
>int fishSleeping();
>int fishProCreating();
>
>FISH_STATE		pfnFishState;
>
>/* the main function */
>int main( void )
>{
>   int i;
>   
>   pfnFishState = fishSwimming;
>
>   /* duty cycle */
>   for( i=0; i<999; i++ )
>   {
>      /* call the function of the current state */
>      pfnFishState();
>   }
>}
>
>int fishSwimming()
>{
>   printf( "swimming\n" );
>   /* is food near */
>   if( food_is_near )
>   {
>      pfnFishState = fishEating;
>   }
>
>   if( time_for_bed )
>   {
>     pfnFishState = fishSleeping;
>   }
>
>   /* ..... and so on ..... */
>}
>
>Does this help at all?
>
>
>Rob Humphris
>
>>
>
---------------------------------------------------------------
Guilherme Silveira - Sao Paulo - Brasil
carlos AT usway DOT com - thedarkage AT mail DOT geocities DOT com
http://www.geocities.com/SiliconValley/Way/5441/
18/09/1981 - Until Today...