gotos

[Charles Lambert]

In article <27310 at cca.CCA.COM> g-rh at CCA.CCA.COM.UUCP (Richard Harter) writes:
>
>f)	Put the test condition in a while statement and step through the
>	actions [somehow].  Unfortunately, I don't see a nice way to do
>	this in C.  The thought that first occurs to one is something like
>
>for (step=0,done=0;!done;step++) {
>  switch(step) {
>    case 0:  action_0;
>             break;
>    case 1:  action_1;
>             break;
>    ......
>    default: done = 1;
>             break;
>    }
>  if (!done && test_condition) done=1;
>  }

This is almost a finite-state machine, and state machine programming is an
accepted idiom. Generalise it as follows:

state=STAT0;
while ( state != STATE_DONE ) {
    switch (state) {

    STATE0: action_0();
	    if (exit_condition_0)
		state = STATE_DONE;
	    else
		state=STATE1;
	    break;
    STATE1: action_1();
	    if (exit_condition_1)
		state = STATE_DONE;
	    else
		state = STATE2;
	    break;
    .
    .
    .
    }
}

Note that with this model,  states may occur in any order and even
repetitively.  The "if...goto" construct is simply a sequential case of the
general state machine.

-----------------
Charles Lambert