So I got a PHP question in a paper. The question is to write the output of the given code.
$x = 5;
echo $x;
echo "<br />";
echo $x+++$x++;
echo "<br />";
echo $x;
echo "<br />";
echo $x---$x--;
echo "<br />";
echo $x;
So my answer was
5
12
5
0
5
This is what everyone wrote because it's the logically correct answer but when we practically implemented it the output was this.
5
11
7
1
5
Can someone explain to me how and why PHP would give this output? It's very confusing.
One thing you need to know is that $x++ uses the value, then increments it, while $x-- uses the value, the decrements it. So break down the code:
$x = 5; // Easy enough
echo $x++ + $x++; // X is first 5. Use it, then increment it. X is now 6, use it, then increment it. 5+6 = 11
echo $x; // Since we incremented it again on the previous line, x is now 7.
echo $x-- - $x--; // Use 7, decrement (x is now 6), subtract X, then decrement it. 7 - 6 = 1
echo $x; // X is now 5
See https://www.php.net/manual/en/language.operators.increment.php , it has more information and examples on how it works.