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From: judith@mit-amt.MIT.EDU (Judith Donath)
Newsgroups: net.lang.c
Subject: are for loops and while loops the same thing?
Message-ID: <139@mit-amt.MIT.EDU>
Date: Fri, 4-Apr-86 20:15:09 EST
Article-I.D.: mit-amt.139
Posted: Fri Apr  4 20:15:09 1986
Date-Received: Sun, 6-Apr-86 01:10:45 EST
Organization: MIT Media Lab, Cambridge, MA
Lines: 50
Keywords: for, while, continue

K & R, page 56:
	"The for statement
		for (expr1; expr2; expr3)
			statement
	is equivalent to
		expr 1;
		while (expr2) {
			statement
			expr3;
		}"
		
Not always true.

K & R, page 62
	"The continue statement... causes the next iteration of the 
	enclosing loop (for, while, do) to begin.  In the whie and do, this
	means that the test part is executed immediately; in the for, control
	passes to the re-initialization step."

Thus, a loop like
	for (i = 0; i < 4; i++)
	    {
	    if (i == 2)
		{
		printf("continuing\n");
		continue;
		}
	    else
		printf("%d\n", i);
	    }
terminates, while

	i = 0;
	while (i < 4)
	    {
	    if (i == 2)
		{
		printf("continuing\n");
		continue;
		}
	    else
		printf("%d\n");
	    i++;
	    }
loops forever.

Is there any reason or use for this difference in behaviour between 
while and for?  Are there any implementations in which a continue 
in a for loop passes control to the test, as if for was really
the equivalent of the above structured while loop?