What are common mistakes when using strtotime() function in PHP for date manipulation?

Common mistakes when using strtotime() function in PHP for date manipulation include not providing a valid date string or not considering the timezone when converting dates. To avoid these issues, always ensure that the date string is in a valid format and consider setting the timezone explicitly.

// Example of using strtotime() function with valid date string and timezone set
$dateString = "2022-01-01";
$timestamp = strtotime($dateString);
$date = date('Y-m-d', $timestamp);

// Set timezone explicitly
date_default_timezone_set('America/New_York');
$timestamp = strtotime($dateString);
$date = date('Y-m-d', $timestamp);