PHP Function: Cal_JDMonthName

In PHP, we have access to a variety of built-in functions that can make our coding experience more efficient and streamlined. One such function is cal_jdmonthname, which is used to return the month name for a specified Julian day count.

What is a Julian day count?

Before we dive into how the cal_jdmonthname function works, it's essential to understand what a Julian day count is. A Julian day count is a continuous count of days that started at noon on January 1st, 4713 BCE. It is named after Julius Caesar, who introduced it in 45 BCE as part of the Julian calendar.

What does the cal_jdmonthname function do?

The cal_jdmonthname function takes two parameters: the Julian day count and a boolean value that determines whether the month name should be abbreviated or not. If the boolean value is set to true, the function returns an abbreviated three-letter month name. If it's set to false, the function returns the full month name.

Here's an example:

$jd = cal_to_jd(CAL_GREGORIAN, date("m"), date("d"), date("Y"));
echo "Today is " . cal_jdmonthname($jd, CAL_MONTH_GREGORIAN_LONG) . ".";

This code will output something like "Today is March."

How to use the cal_jdmonthname function?

To use the cal_jdmonthname function in your PHP code, you need to follow these steps:

  1. Determine the Julian day count for the date you're interested in. You can use the cal_to_jd function to convert a Gregorian date to a Julian day count.
  2. Call the cal_jdmonthname function, passing in the Julian day count and the boolean value that determines whether the month name should be abbreviated or not.
  3. Use the returned value in your code as needed.


Let's say you want to display a calendar for the month of March 2023. Here's how you can use the cal_jdmonthname function to do that:

$jd = gregoriantojd(3, 1, 2023);
echo "<h1>March 2023</h1>";
echo "<table>";
echo "<tr><th>Sun</th><th>Mon</th><th>Tue</th><th>Wed</th><th>Thu</th><th>Fri</th><th>Sat</th></tr>";
for ($i = 1; $i <= 31; $i++) {
    $day = cal_jdweekday(cal_to_jd(CAL_GREGORIAN, 3, $i, 2023), CAL_DOW_LONG);
    if ($i == 1) {
        echo "<tr>";
        for ($j = 0; $j < $day; $j++) {
            echo "<td></td>";
    echo "<td>$i<br>" . cal_jdmonthname(cal_to_jd(CAL_GREGORIAN, 3, $i, 2023), CAL_MONTH_GREGORIAN_SHORT) . "</td>";
    if ($day == CAL_DOW_SAT) {
        echo "</tr>";
echo "</table>";

This code will output a calendar for the month of March 2023, with the month name abbreviated to three letters.

Benefits of using the cal_jdmonthname function

Using the cal_jdmonthname function can make working with Julian day counts in PHP much easier and more efficient. Here are a few benefits of using this function:

  1. Saves time: Instead of manually calculating the month name for a given Julian day count, you can simply call the cal_jdmonthname function.
  2. Consistency: The function ensures that you get the correct month name every time, which reduces the risk of errors in your code.
  3. Flexibility: The function allows you to specify whether you want the full month name or an abbreviated version, which gives you more control over how your code displays information.


Overall, the cal_jdmonthname function is a valuable tool for PHP developers who need to work with Julian day counts. By using this function in your code, you can save time, ensure consistency, and have more flexibility in how you display information to users.

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