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Online Sandbox for SQL and PHP: Write, Run, Test, and Share SQL Queries and PHP Code
<?php
function showMem($label) {
echo "$label: " . round(memory_get_usage() / 1024, 2) . " KB\n";
}
showMem('Start');
$a = str_repeat('x', 1024 * 1024); // 1 MB string
showMem('After creating $a');
$b = $a;
$c = $a;
$d = $a;
showMem('After assigning $b = $a');
$b[0] = 'y'; // triggers COW because string is immutable
showMem('After modifying $b[0]');