Script Hangs from Infinite Loop

Why This Happens

Infinite loops occur when a loop's exit condition is never satisfied. Unlike recursion depth errors, infinite loops silently hang until the maximum execution time is reached. Common causes include forgetting to increment a counter, modifying the wrong variable, or a condition that is logically always true.

The Problem

$items = [1, 2, 3, 4, 5];
$i = 0;
while ($i < count($items)) {
    if ($items[$i] % 2 === 0) {
        array_splice($items, $i, 1); // Removes item but doesn't adjust $i correctly
    }
    $i++;
}

The Fix

// Option 1: Use array_filter
$items = [1, 2, 3, 4, 5];
$items = array_filter($items, fn($item) => $item % 2 !== 0);

// Option 2: Loop backwards
$items = [1, 2, 3, 4, 5];
for ($i = count($items) - 1; $i >= 0; $i--) {
    if ($items[$i] % 2 === 0) {
        array_splice($items, $i, 1);
    }
}

Step-by-Step Fix

1. 1

   Identify the loop

   Add logging or echo statements inside the loop to track iterations. Check if the loop variable is changing as expected.

2. 2

   Verify the exit condition

   Check that the loop condition will eventually become false. Verify counter increments, collection modifications, and boolean flag updates.

3. 3

   Use safe alternatives

   Prefer array functions like array_filter, array_map, or for loops with clear bounds over while loops with complex conditions.