From: drieux <[EMAIL PROTECTED]>
> On Friday, July 26, 2002, at 07:58 , Connie Chan wrote:
> > And one more quick question. What are the meanings of
> > "Expression" and "Block" , what are there difference ?
>
> an 'expression' is something that can be resolved,
>
> my $val = "foo";
> my $foo = 1 + $val;
> my $bar = translate(@list);
If you did not include the semicolons I'd agree those are
expressions.
But even then I guess this would be a little misleading. While in
Perl you can use those as expressions, it's not usual. These are not
good examples IMHO.
These are all expressions:
1
1 + 2
$x * 2
foo(1,2,3) + 49
(1,2) x 2
$x == $y
$x < 5
$x > 1 && $x < 5
but even this is an expression:
$x = $y + 2
Basicaly "expression" is something that creates a value that you can
assign to a variable, pass to a function or use as a condition.
This means that
$x = $y + 2
IS an expression, but
$x = $y + 2;
IS NOT! It's a statement.
Try
if ($x = $y + 2) {
print "\$y is not -2\n";
} else {
print "\$y is -2\n";
}
and
if ($x = $y + 2;) {
print "\$y is not -2\n";
} else {
print "\$y is -2\n";
}
Jenda
=========== [EMAIL PROTECTED] == http://Jenda.Krynicky.cz ==========
There is a reason for living. There must be. I've seen it somewhere.
It's just that in the mess on my table ... and in my brain
I can't find it.
--- me
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