Online PHP editor | output for Aacol

@ 2026-04-10T08:23:43Z

<?php

// distance between two 2D points
$x1 = 3; $y1 = 4;
$x2 = 7; $y2 = 1;

$dist = hypot($x2 - $x1, $y2 - $y1); // 5.0

// why not just sqrt(($dx)**2 + ($dy)**2)?
// because hypot() avoids intermediate overflow

// QUICK TIP STRAIGHT FROM GAME DEV: sometimes you only want to *compare* distances, and
// square root is SLOW
// in this case, just compare squared values, it's equivalent!
$dx1 = $x2 - $x1;
$dy1 = $y2 - $y1;
$dist1Sq = $dx1 * $dx1 + $dy1 * $dy1;

// some other points in space...
$dist2Sq = $dx2 * $dx2 + $dy2 * $dy2;

if ($dist1Sq < $dist2Sq) { // squared value compared, way faster without square root!
    echo "Point 2 is closer to Point 1\n";
} else {
    echo "Point 3 is closer to Point 1\n";
}

Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.21, 8.5.0 - 8.5.6: Warning: Undefined variable $dx2 in /in/Aacol on line 20 Warning: Undefined variable $dx2 in /in/Aacol on line 20 Warning: Undefined variable $dy2 in /in/Aacol on line 20 Warning: Undefined variable $dy2 in /in/Aacol on line 20 Point 3 is closer to Point 1
Output for 5.0.4 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33: Notice: Undefined variable: dx2 in /in/Aacol on line 20 Notice: Undefined variable: dx2 in /in/Aacol on line 20 Notice: Undefined variable: dy2 in /in/Aacol on line 20 Notice: Undefined variable: dy2 in /in/Aacol on line 20 Point 3 is closer to Point 1
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.3: Notice: Undefined variable: dx2 in /in/Aacol on line 20 Notice: Undefined variable: dx2 in /in/Aacol on line 20 Notice: Undefined variable: dy2 in /in/Aacol on line 20 Notice: Undefined variable: dy2 in /in/Aacol on line 20 Point 3 is closer to Point 1

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