PHP strtotime() And mktime(): Convert Date To Timestamp

Both strtotime() and mktime() are PHP functions used to convert a date or time into a Unix timestamp, which represents the number of seconds that have elapsed since January 1, 1970.

Here's a brief overview of each function and how they differ:

strtotime(): This function parses a string containing a US English date format and produces a Unix timestamp.

Here's the basic syntax:

strtotime(string, now)

string: The string to parse. It can be a date, time, or a string with relative date/time formats (like "next Monday", "+1 day", etc.).
now (optional): The timestamp used to calculate relative dates. If not provided, the current time is used.

Example:

echo strtotime("now"); // Outputs: current Unix timestamp
echo strtotime("10 September 2023"); // Outputs: Unix timestamp for September 10, 2023
echo strtotime("+1 day"); // Outputs: Unix timestamp for one day from now

mktime(): This function generates a Unix timestamp given the date components like hour, minute, second, month, day, and year.

Here's the basic syntax:

mktime(hour, minute, second, month, day, year)

hour, minute, second: The hour, minute, and second. If not provided, they default to current time.
month, day, year: The month, day, and year. If not provided, they default to current date.

Example:

echo mktime(0, 0, 0, 9, 10, 2023); // Outputs: Unix timestamp for September 10, 2023

In summary, use strtotime() when you have a date or time in string format, and use mktime() when you have a date or time in numerical format. Both functions can handle a wide range of dates, from years in the past to many years in the future.

Convert date to timestamp in PHP with strtotime() and mktime():

<?php
$dateString = "2023-01-01";

// Using strtotime()
$timestamp1 = strtotime($dateString);

// Using mktime()
list($year, $month, $day) = explode('-', $dateString);
$timestamp2 = mktime(0, 0, 0, $month, $day, $year);

echo $timestamp1; // Outputs: Unix timestamp for January 1, 2023
echo $timestamp2; // Outputs the same Unix timestamp

PHP strtotime() and mktime() examples:

<?php
// Using strtotime()
$timestamp1 = strtotime("2023-01-01");

// Using mktime()
$timestamp2 = mktime(0, 0, 0, 1, 1, 2023);

echo $timestamp1; // Outputs: Unix timestamp for January 1, 2023
echo $timestamp2; // Outputs the same Unix timestamp

Using mktime() to create a timestamp from date components in PHP:

<?php
$timestamp = mktime(12, 30, 0, 3, 15, 2023);

echo $timestamp; // Outputs: Unix timestamp for March 15, 2023, at 12:30 PM

Convert string to timestamp using mktime() in PHP:

<?php
$dateString = "2023-01-01";
list($year, $month, $day) = explode('-', $dateString);
$timestamp = mktime(0, 0, 0, $month, $day, $year);

echo $timestamp; // Outputs: Unix timestamp for January 1, 2023

Generating timestamps with mktime() in PHP:

<?php
$timestamp = mktime(12, 0, 0, date('n'), date('j'), date('Y'));

echo $timestamp; // Outputs: Unix timestamp for today at 12:00 PM

Convert date and time to timestamp with PHP mktime() and strtotime():

<?php
$dateTimeString = "2023-01-01 12:30:00";

// Using strtotime()
$timestamp1 = strtotime($dateTimeString);

// Using mktime()
list($date, $time) = explode(' ', $dateTimeString);
list($year, $month, $day) = explode('-', $date);
list($hour, $minute, $second) = explode(':', $time);
$timestamp2 = mktime($hour, $minute, $second, $month, $day, $year);

echo $timestamp1; // Outputs: Unix timestamp for January 1, 2023, at 12:30 PM
echo $timestamp2; // Outputs the same Unix timestamp

mktime() function for handling future and past dates in PHP:

<?php
// Current timestamp
$currentTimestamp = time();

// Future date
$futureTimestamp = mktime(0, 0, 0, date('n'), date('j') + 7, date('Y'));

// Past date
$pastTimestamp = mktime(0, 0, 0, date('n'), date('j') - 7, date('Y'));

echo $currentTimestamp; // Outputs: Current Unix timestamp
echo $futureTimestamp;  // Outputs: Unix timestamp for the date 7 days from now
echo $pastTimestamp;    // Outputs: Unix timestamp for the date 7 days ago

PHP mktime() for date calculations and manipulation:

<?php
// Adding 2 days to the current date
$futureDate = date('Y-m-d', mktime(0, 0, 0, date('n'), date('j') + 2, date('Y')));

echo $futureDate; // Outputs: Date 2 days from now in "YYYY-MM-DD" format

Using strtotime() and mktime() together for advanced date handling in PHP:

<?php
$dateString = "2023-01-01";
$timestamp1 = strtotime($dateString);

list($year, $month, $day) = explode('-', $dateString);
$timestamp2 = mktime(0, 0, 0, $month, $day, $year);

echo $timestamp1; // Outputs: Unix timestamp for January 1, 2023
echo $timestamp2; // Outputs the same Unix timestamp

Date formatting and conversion with PHP strtotime() and mktime():
Both functions can be used in conjunction with date() to format and convert timestamps:
```
<?php
$timestamp = strtotime("2023-01-01");
$formattedDate = date("F j, Y", $timestamp);

echo $formattedDate; // Outputs: January 1, 2023
```