On Wednesday 16 January 2002 17:25, you wrote:
I'm sorry, I think I was confusing languages. PHP does do lazy evaluation. If
the left side is false the right side won't be evaluated. I've attached some
code, it ain't really neat & tidy but it's effective and will show you how it
works. Just run it
> aha! see, i didn't understand the whole picture. so, let me see if i can
> create another question. suppose
>
> if (($a_good = ($a == 'a')) && ($b_good = ($b == 'b'))) blahblahblah();
>
> are you saying, that $b_good should always have the result of ($b == 'b')
> even if $a != 'a'? that's not what my test shows (hi bogdan :)
>
> so, is there something other than && that forces the other half to be
> evaluated?
>
> interesting...
> mike
>
> on 8/23/01 5:19 PM, TD - Sales International Holland B.V. at
> [EMAIL PROTECTED]
>
> wrote:
> > On Wednesday 16 January 2002 16:18, you wrote:
> >
> > I think the cause is, which is lacking in the reply below, that if you
> > have like
> > if ((function1(val, val)) && (function2(val, val)) blabla();
> >
> > you still want function2 to be executed because it does things necessary
> > for your script, however, if one of them returns false you don't want
> > blabla() to be executed. If that isn't the case you should use or or one
> > of the other operators
> >
> > not too sure about that tho' but i'm sure I'll be corrected if that isn't
> > the case :-)
> >
> >> on 1/16/02 5:57 AM, Miles Thompson at [EMAIL PROTECTED]
wrote:
> >>> For "or" statements it does, but not && or xor. I don't know about you,
> >>> but I wouldn't want lazy evaluation on a conditional statement
> >>> involving "and".
> >>
> >> i'm new to all this stuff, so i'll bite. hopefully someone can explain
> >> what i'm missing.
> >>
> >> if i have a statement like
> >>
> >> if (($a == 'a') && ($b == 'b')) blahblahblah();
> >>
> >> and, $a != 'a'.
> >>
> >> why should php even look at the value for $b while evaluating this line?
> >> shouldn't the if fail after evaluating $a?
> >>
> >> thanks,
> >> mike
> >>
> >> -- mike cullerton michaelc at cullerton dot com
>
> -- mike cullerton michaelc at cullerton dot com
<?
/* This is to test whether or not && evaluates both sides if the left side is false */
function tr() {
print "This function returns true<BR>\n";
return TRUE;
}
function fl() {
print "This function returns false<BR>\n";
return FALSE;
}
print "<HTML><HEAD><TITLE>The Logical Operator && Test</TITLE></HEAD><BODY><H1>The Logical Operator && Test</H1>\n";
print "<CENTER>True && True then echo succes<BR>\n";
if (tr() && tr()) echo "Succes<BR>\n";
print "<HR>\n";
print "True && False then echo succes<BR>\n";
if (tr() && fl()) echo "Succes<BR>\n";
print "<HR>\n";
print "<CENTER>False && True then echo succes<BR>\n";
if (fl() && tr()) echo "Succes<BR>\n";
print "<HR>\n";
print "<CENTER>False && False then echo succes<BR>\n";
if (fl() && fl()) echo "Succes<BR>\n";
print "<HR>\n";
print "</CENTER></BODY></HTML>";
?>
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