Logical operators or assignment in Perl cannot work?

Question

I want to check my variable $id is equal 497 or equal 200 , if $id not equal 497 or $id not equal 200 then mail, but when i run the example as below, I set $id =497 by hand , but run the code ,it's print "not equal\n";

my $id = 497; if($id != 497 || $id != 200) { print "not equal\n"; } else { print "equal , not to mail\n"; }

If you're comfortable with mathematical logic notation, you might want to read about De Morgan's laws. They describe how a condition like “equal to 497 or equal to 200” must be negated. In Perl code: !($x || $y) == !$x && !$y, and !($x && $y) == !$x || !$y. — amon
– amon, Commented Oct 18, 2018 at 7:10

ysth · Accepted Answer · 2018-10-18 05:43:25Z

It says not equal because $id != 200 is true. || returns true if either operand is true.

You want to say:

if ($id != 497 && $id != 200)

so not equal is printed only when $id is neither 497 or 200.

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