Strange print behaviour in PHP?

Question

Why does the following code output 128?

<?php 
    print 4 << 5; 
?>

See manual of bitwise operators: http://www.php.net/manual/en/language.operators.bitwise.php — ghkaren, Mar 15 '12 at 11:26

score 15 · Accepted Answer · edited Dec 30 '15 at 18:31

15

Because it's a bitwise operator. I think it means 4 multiplied to 2^5 because that operator means

Shift the bits of $a $b steps to the left (each step means "multiply by two")

so it's five steps. It's 4 * 2 * 2 * 2 * 2 * 2 (But I'm guessing here; everything happens at bit level).

edited Dec 30 '15 at 18:31

Peter Mortensen

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answered Mar 15 '12 at 11:25

Nicola Peluchetti

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score 15 · Answer 2 · edited Dec 30 '15 at 18:33

15

Refer to Bitwise Operators:

We have to find 4 << 5. It means shift the bits of 4 5 times to the left:

4 is 00000000000000000000000000000100
4 << 5 after shifting is 00000000000000000000000010000000
00000000000000000000000010000000 is 2^7 = 2*2*2*2*2*2*2 = 128

edited Dec 30 '15 at 18:33

Peter Mortensen

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answered Mar 15 '12 at 11:41

Mithun Satheesh

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+1 for the example. Reminds me I have to learn how *bitwise operators actually work*. :) – Amal Murali Nov 18 '13 at 05:46

Strange print behaviour in PHP?

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