Xref: utzoo comp.lang.c:9796 comp.software-eng:501
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From: cl@datlog.co.uk (Charles Lambert)
Newsgroups: comp.lang.c,comp.software-eng
Subject: Re: gotos
Message-ID: <760@dlhpedg.co.uk>
Date: 28 Apr 88 12:51:30 GMT
References: <1988Apr8.183815.3187@utzoo.uucp> <449@goofy.megatest.UUCP> <2200@louie.udel.EDU> <587@vsi.UUCP> <27310@cca.CCA.COM>
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In article <27310@cca.CCA.COM> g-rh@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