PHP Date and Time

<?php
$now = time(); // Unix timestamp

// Format characters
echo date("Y");        // 2024 (4-digit year)
echo date("m");        // 01-12 (month)
echo date("d");        // 01-31 (day)
echo date("H");        // 00-23 (hour)
echo date("i");        // 00-59 (minutes)
echo date("s");        // 00-59 (seconds)
echo date("D");        // Mon, Tue... (short day)
echo date("l");        // Monday, Tuesday... (full day)
echo date("N");        // 1=Mon ... 7=Sun
echo date("t");        // days in current month

// Common formats
echo date("Y-m-d");           // 2024-01-15
echo date("d/m/Y");           // 15/01/2024
echo date("D, d M Y H:i:s"); // Mon, 15 Jan 2024 14:30:00
echo date("r");               // RFC 2822 formatted date

// mktime — create timestamp for specific date
$ts = mktime(12, 0, 0, 6, 15, 2024); // noon on June 15, 2024
echo date("Y-m-d H:i:s", $ts); // 2024-06-15 12:00:00
?>

<?php
echo date("Y-m-d", strtotime("2024-01-15"));   // 2024-01-15
echo date("Y-m-d", strtotime("next Monday"));  // next Monday's date
echo date("Y-m-d", strtotime("+1 week"));      // 7 days from now
echo date("Y-m-d", strtotime("+1 month"));     // 1 month from now
echo date("Y-m-d", strtotime("-1 year"));      // 1 year ago
echo date("Y-m-d", strtotime("last day of this month")); // end of month
?>

<?php
// Create DateTime objects
$now   = new DateTime();
$birth = new DateTime("1995-06-15");

// Format
echo $now->format("Y-m-d H:i:s");

// Modify
$now->modify("+30 days");
echo $now->format("Y-m-d");

// Date difference
$diff = $now->diff($birth);
echo $diff->y . " years, " . $diff->m . " months, " . $diff->d . " days";

// DateTimeImmutable — does not modify original
$date = new DateTimeImmutable("2024-01-01");
$next = $date->modify("+1 year"); // returns new object
echo $date->format("Y"); // 2024 (unchanged)
echo $next->format("Y"); // 2025

// Create from format
$d = DateTime::createFromFormat("d/m/Y", "25/12/2024");
echo $d->format("Y-m-d"); // 2024-12-25
?>