Calendar in PHP: A Comprehensive Guide

Hello to all programmer friends! Today we aim to discuss one of the interesting and practical features of the PHP language: calendar. Exploring this topic is not only useful for those who are new to web programming, but also for professionals who may find it beneficial as well.

Furthermore, calendars are used as part of many applications and websites. Scheduling, reservation, and time management, all heavily rely on calendars. Without a calendar, programming related to dates and events would not have significant meaning. By using PHP, you can design a simple and user-friendly calendar that allows users to view important dates and events.

In this article, I will hint at a simple and understandable method for creating a calendar in PHP. The first step for this task is to familiarize yourself with various PHP functions related to date and time management. Then, step by step, we will create a simple calendar.

One of the built-in functions in PHP for managing dates and times is the date() function. This function allows you to retrieve information such as the day, month, year, and hour. For example:

<?php
    $date = date('Y-m-d'); // date format: year-month-day
    echo "Today's date is: " . $date;
?>

In this piece of code, we use the date() function to get today's date in the format Y-m-d (year-month-day) and print it out.

Now, let’s move one step further and create a simple calendar. Consider the code below:

<?php
function build_calendar($month, $year) {
    // First, we get the first day of the month
    $first_day_of_month = mktime(0, 0, 0, $month, 1, $year);
    $days_in_month = date('t', $first_day_of_month);
    $date_components = getdate($first_day_of_month);
    $month_name = $date_components['month'];
    $day_of_week = $date_components['wday'];

    // Start building the HTML calendar
    $calendar = "<table>\r\n";
    $calendar .= "<caption>$month_name $year</caption>\r\n";
    $calendar .= "<tr>\r\n";

    // Days of the week
    $days_of_week = array('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday');
    foreach($days_of_week as $day) {
        $calendar .= "<th>$day</th>\r\n";
    }
    $calendar .= "</tr><tr>\r\n";

    // Adjust the position of the first day
    if ($day_of_week > 0) {
        for($k=0;$k<$day_of_week;$k++) {
            $calendar .= "<td></td>\r\n";
        }
    }

    $current_day = 1;

    // Fill in the days of the month
    while ($current_day <= $days_in_month) {
        if ($day_of_week == 7) {
            $day_of_week = 0;
            $calendar .= "</tr><tr>\r\n";
        }

        $calendar .= "<td>$current_day</td>\r\n";
        $current_day++;
        $day_of_week++;
    }

    if ($day_of_week != 7) {
        $remaining_days = 7 - $day_of_week;
        for($i=0;$i<$remaining_days;$i++) {
            $calendar .= "<td></td>\r\n";
        }
    }

    $calendar .= "</tr>\r\n";
    $calendar .= "</table>\r\n";

    return $calendar;
}

// Show the calendar for the current month
echo build_calendar(date('m'), date('Y'));
?>

Code Explanation: