PHP Date and Time

Date and Time Functions

<?php
echo date("Y-m-d");
// 2025-10-02
?>

<?php
echo time();
// 1727884800
?>

<?php
echo strtotime("next Monday");
?>

<?php
echo mktime(0, 0, 0, 12, 25, 2025);
?>

🔹 Basic Date Display

Display current date in various formats:

<?php
// Current date in different formats
echo "Today is " . date("Y-m-d") . "<br>";
// Output: Today is 2025-10-02

echo "Today is " . date("d/m/Y") . "<br>";
// Output: Today is 02/10/2025

echo "Today is " . date("l, F j, Y") . "<br>";
// Output: Today is Thursday, October 2, 2025

echo "Current time is " . date("h:i:s A") . "<br>";
// Output: Current time is 03:30:45 PM

echo "Current date and time: " . date("Y-m-d H:i:s") . "<br>";
// Output: Current date and time: 2025-10-02 15:30:45
?>

🔹 Date Format Characters

Common format characters for the date() function:

<?php
echo date("d") . "<br>";      // 02
echo date("D") . "<br>";      // Thu
echo date("l") . "<br>";      // Thursday
echo date("m") . "<br>";      // 10
echo date("M") . "<br>";      // Oct
echo date("F") . "<br>";      // October
echo date("Y") . "<br>";      // 2025
echo date("H:i:s") . "<br>";  // 15:30:45
?>

🔹 Working with Timestamps

Unix timestamp represents seconds since January 1, 1970:

<?php
// Get current timestamp
$timestamp = time();
echo "Current timestamp: " . $timestamp . "<br>";
// Output: Current timestamp: 1727884800

// Convert timestamp to readable date
echo "Date: " . date("Y-m-d H:i:s", $timestamp) . "<br>";
// Output: Date: 2025-10-02 15:30:45

// Create timestamp for specific date
$christmas = mktime(0, 0, 0, 12, 25, 2025);
echo "Christmas 2025: " . date("l, F j, Y", $christmas) . "<br>";
// Output: Christmas 2025: Thursday, December 25, 2025

// Convert string to timestamp
$nextWeek = strtotime("+1 week");
echo "Next week: " . date("Y-m-d", $nextWeek) . "<br>";
// Output: Next week: 2025-10-09
?>

🔹 Date Calculations

Perform calculations with dates using strtotime():

<?php
// Current date
$today = date("Y-m-d");
echo "Today: " . $today . "<br>";

// Tomorrow
$tomorrow = date("Y-m-d", strtotime("+1 day"));
echo "Tomorrow: " . $tomorrow . "<br>";

// Next week
$nextWeek = date("Y-m-d", strtotime("+1 week"));
echo "Next week: " . $nextWeek . "<br>";

// Next month
$nextMonth = date("Y-m-d", strtotime("+1 month"));
echo "Next month: " . $nextMonth . "<br>";

// Last year
$lastYear = date("Y-m-d", strtotime("-1 year"));
echo "Last year: " . $lastYear . "<br>";

// Specific date
$specificDate = date("Y-m-d", strtotime("2025-12-25"));
echo "Christmas: " . $specificDate . "<br>";

// Next Monday
$nextMonday = date("Y-m-d", strtotime("next Monday"));
echo "Next Monday: " . $nextMonday . "<br>";
?>

🔹 Calculate Date Difference

Find the difference between two dates:

<?php
// Method 1: Using timestamps
$date1 = strtotime("2025-10-02");
$date2 = strtotime("2025-12-25");

$diff = $date2 - $date1;
$days = floor($diff / (60 * 60 * 24));

echo "Days until Christmas: " . $days . " days<br>";
// Output: Days until Christmas: 84 days

// Method 2: Using DateTime objects
$datetime1 = new DateTime("2025-10-02");
$datetime2 = new DateTime("2025-12-25");

$interval = $datetime1->diff($datetime2);
echo "Difference: " . $interval->days . " days<br>";
echo "Or: " . $interval->m . " months and " . $interval->d . " days<br>";

// Calculate age
$birthdate = new DateTime("1990-05-15");
$today = new DateTime();
$age = $birthdate->diff($today);
echo "Age: " . $age->y . " years old<br>";
?>

🔹 DateTime Class

Object-oriented approach to working with dates:

<?php
// Create DateTime object
$date = new DateTime();
echo "Current date: " . $date->format('Y-m-d H:i:s') . "<br>";

// Create specific date
$specificDate = new DateTime('2025-12-25');
echo "Christmas: " . $specificDate->format('l, F j, Y') . "<br>";

// Modify date
$date->modify('+1 month');
echo "Next month: " . $date->format('Y-m-d') . "<br>";

$date->modify('-2 weeks');
echo "Two weeks ago: " . $date->format('Y-m-d') . "<br>";

// Set timezone
$date->setTimezone(new DateTimeZone('America/New_York'));
echo "New York time: " . $date->format('Y-m-d H:i:s T') . "<br>";

// Add interval
$date->add(new DateInterval('P10D')); // Add 10 days
echo "After 10 days: " . $date->format('Y-m-d') . "<br>";
?>

🔹 Timezone Handling

Work with different timezones:

<?php
// Set default timezone
date_default_timezone_set('America/New_York');
echo "New York: " . date('Y-m-d H:i:s') . "<br>";

// Get all timezones
$timezones = DateTimeZone::listIdentifiers();
echo "Total timezones: " . count($timezones) . "<br>";

// Create date with specific timezone
$date = new DateTime('now', new DateTimeZone('Asia/Tokyo'));
echo "Tokyo: " . $date->format('Y-m-d H:i:s T') . "<br>";

// Convert between timezones
$date->setTimezone(new DateTimeZone('Europe/London'));
echo "London: " . $date->format('Y-m-d H:i:s T') . "<br>";

// Get timezone offset
$timezone = new DateTimeZone('America/Los_Angeles');
$datetime = new DateTime('now', $timezone);
$offset = $timezone->getOffset($datetime);
echo "UTC offset: " . ($offset / 3600) . " hours<br>";
?>

🔹 Practical Date Examples

Real-world date and time applications:

<?php
// Check if date is weekend
function isWeekend($date) {
    $dayOfWeek = date('N', strtotime($date));
    return ($dayOfWeek >= 6);
}

echo "Is today weekend? " . (isWeekend('2025-10-02') ? "Yes" : "No") . "<br>";

// Get first day of month
$firstDay = date('Y-m-01');
echo "First day of month: " . $firstDay . "<br>";

// Get last day of month
$lastDay = date('Y-m-t');
echo "Last day of month: " . $lastDay . "<br>";

// Count days in month
$daysInMonth = date('t');
echo "Days in this month: " . $daysInMonth . "<br>";

// Get week number
$weekNumber = date('W');
echo "Week number: " . $weekNumber . "<br>";

// Check if leap year
$year = 2024;
$isLeap = date('L', mktime(0, 0, 0, 1, 1, $year));
echo "$year is " . ($isLeap ? "a leap year" : "not a leap year") . "<br>";

// Format for database
$dbDate = date('Y-m-d H:i:s');
echo "Database format: " . $dbDate . "<br>";

// Human-readable time ago
function timeAgo($timestamp) {
    $diff = time() - $timestamp;
    if ($diff < 60) return $diff . " seconds ago";
    if ($diff < 3600) return floor($diff / 60) . " minutes ago";
    if ($diff < 86400) return floor($diff / 3600) . " hours ago";
    return floor($diff / 86400) . " days ago";
}

$pastTime = strtotime('-2 hours');
echo "Posted: " . timeAgo($pastTime) . "<br>";
?>