当日、当周、当月的开始、结束时间

<?php

// $now = 1631697213;

$now = time();

// 当日开始、结束时间戳

echo date("Y-m-d 00:00:00", $now) . PHP_EOL;

echo date("Y-m-d 23:59:59", $now) . PHP_EOL;

// 当周开始、结束时间戳

echo date('Y-m-d 00:00:00', strtotime('this week monday', $now)) . PHP_EOL;

echo date('Y-m-d 23:59:59', strtotime('this week sunday', $now)) . PHP_EOL;

// 当月开始、结束时间戳

echo date('Y-m-d 00:00:00', strtotime('first day of this month', $now)) . PHP_EOL;

echo date('Y-m-d 23:59:59', strtotime('last day of this month', $now)) . PHP_EOL;