怎么理解 谢谢！

Question

<?php

$x = 5;

$y = 6;

$foo = $x++ + $x--;

$bar = ++$y + ++$x;

$cup = $x-- + $y--;

$paper = ++$x + $x++;

$water = $y-- + $x--;

echo $y--.'<br>';//等于5

echo $x--.'<br>';//等于6

//这里怎么理解。。。

echo $water.'<br>';//等于13

echo $paper.'<br>';//等于12

echo $water + $paper;//等于25

?>

Answer 1

How to understand? Thank you! -PHP Chinese website Q&A-How to understand Thank you! -PHP Chinese website Q&A

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Answer 2

I don’t know