PHP 8 Code Lab.

<?php

// ── Snippet 1: Intermediate variables ────────────────────────────────────────
// Each assignment allocates a new zval (PHP internal value container).
// $tempVar and $tempVar1 linger until garbage collection.

$originalVariable = "  hello world  ";
$tempVar           = strtoupper($originalVariable);   // new allocation
$tempVar1          = trim($tempVar);                  // another new allocation
$originalVariable  = $tempVar1;                       // copy reference back

echo $originalVariable . "\n"; // HELLO WORLD

// $tempVar and $tempVar1 still occupy memory here until scope ends
// or GC runs — wasteful for large strings or tight loops.


// ── Snippet 2: Reassigning the original variable ──────────────────────────────
// PHP uses copy-on-write (CoW). Reassigning the same variable reuses
// the zval slot once the old reference count drops to zero.
// No extra variables = no extra GC overhead.

$originalVariable = "  hello world  ";
$originalVariable = strtoupper($originalVariable);    // refcount drops, reuse
$originalVariable = trim($originalVariable);          // same slot again

echo $originalVariable . "\n"; // HELLO WORLD


// ── Why it matters at scale ───────────────────────────────────────────────────
// In a tight loop over a large dataset the difference is measurable.

$data = array_fill(0, 100000, "  some value  ");

// Slower: creates two extra variables per iteration
$start = microtime(true);
foreach ($data as $item) {
    $step1  = strtoupper($item);
    $step2  = trim($step1);
    $result = $step2;
}
echo "Temp vars:   " . round((microtime(true) - $start) * 1000, 2) . "ms\n";

// Faster: single variable, no extra allocations
$start = microtime(true);
foreach ($data as $item) {
    $item = strtoupper($item);
    $item = trim($item);
}
echo "Reassigned:  " . round((microtime(true) - $start) * 1000, 2) . "ms\n";