Nonequivalent code snippets

[nikolatechie]

Where is the problem?

• In the last two code snippets.

What is the problem?

• After $x = 0;, $y = $x++; is rewritten as $y = $x + 1;, $x++;. These snippets are not equivalent. In the first snippet, $y equals 0 after which $x gets incremented, whereas in the second snippet $y becomes 1 and $x gets incremented.

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Please don't change anything below this point.

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• Build ID: HHVM=HHVM-4.164.0:HSL=v4.108.1:2024-02-08T13:44:46+0000:1fa47f258c6b68f8ec01899aa82fd6ffa0957109
• Page requested: /hack/expressions-and-operators/incrementing-and-decrementing
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• Controller: GuidePageController

[lexidor]

You are correct, $x++ is a post increment. The old value of $x gets used for the assignment. How would you like the statement to be rewritten? Should ++$x be used to restore the described behavior or should a different example be used altogether?

[nikolatechie]

I would suggest just removing + 1 from the second code snippet, as this example would be the easiest to understand. That would look like this:

$x = 0;
$y = $x++; // Parse error

Instead, the above code must be written as statements.

$x = 0;
$y = $x;
$x++;