Date and Time Functions in PHP

Date and time functions are used to display, calculate, format, and manipulate date and time values in PHP applications such as login systems, reports, logs, and bookings.

Exam Definition: Date and time functions are used to handle and manipulate date and time values in PHP.

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Setting Time Zone

Before working with date/time, set the correct time zone.

date_default_timezone_set("Asia/Kolkata");

Exam Tip: Time zone should be set to avoid incorrect time.

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date() Function

Used to format date and time.

Syntax

date(format, timestamp);

Example

echo date("d-m-Y");

Common Date Format Characters

Example: Date & Time

echo date("d-m-Y H:i:s");

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time() Function

Returns current timestamp (seconds since 1 Jan 1970).

echo time();

Exam Line: Timestamp is the number of seconds since Unix Epoch.

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mktime() Function

Creates a timestamp for a specific date/time.

$ts = mktime(10, 30, 0, 5, 20, 2026);
echo date("d-m-Y H:i:s", $ts);

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strtotime() Function

Converts string to timestamp.

echo date("d-m-Y", strtotime("next Monday"));

Real-time Use: Expiry date calculation.

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DateTime Class (Modern Way)

$date = new DateTime();
echo $date->format("d-m-Y");

Date Difference

$d1 = new DateTime("2025-01-01");
$d2 = new DateTime("2026-01-01");
$diff = $d1->diff($d2);
echo $diff->days;

Common Date & Time Functions Summary