Sort a multidimensional array by date element in PHP Last Updated : 11 Jul, 2025 Summarize Comments Improve Suggest changes Share Like Article Like Report Sorting a multidimensional array by element containing date. Use the usort() function to sort the array. The usort() function is PHP builtin function that sorts a given array using user-defined comparison function. This function assigns new integral keys starting from zero to array elements. Syntax: boolean usort( $array, "function_name") Parameters: This function accepts two parameters as shown in the above syntax and are described below: $array: This parameter specifies the array which u want to sort. function_name: This parameter specifies the name of a user-defined function which compares the values and sort the array specified by the parameter $array. This function returns an integer value based on the following conditions. If two argument are equal then it returns 0, If first argument is greater than second, it returns 1 and if first argument is smaller than second, it returns -1. Return Value: This function returns Boolean type value. It returns TRUE in case of success and FALSE in case of failure. We use strtotime to convert given time string to a timestamp object. Once we have timestamps, we subtract them to decide greater. Program: php <?php // Declare a multidimensional array // and initialize it $array = Array ( Array ( "gfg" => "GFG_1", "datetime" => "2019-02-22 11:29:45", ), Array ( "gfg" => "GFG_2", "datetime" => "2019-02-13 11:29:45", ), Array ( "gfg" => "GFG_3", "datetime" => "2019-02-15 11:29:45", ) ); // Comparison function function date_compare($element1, $element2) { $datetime1 = strtotime($element1['datetime']); $datetime2 = strtotime($element2['datetime']); return $datetime1 - $datetime2; } // Sort the array usort($array, 'date_compare'); // Print the array print_r($array) ?> Output: Array ( [0] => Array ( [gfg] => GFG_2 [datetime] => 2019-02-13 11:29:45 ) [1] => Array ( [gfg] => GFG_3 [datetime] => 2019-02-15 11:29:45 ) [2] => Array ( [gfg] => GFG_1 [datetime] => 2019-02-22 11:29:45 ) ) Comment More infoAdvertise with us Next Article Convert timestamp to readable date/time in PHP A aman neekhara Follow Improve Article Tags : Web Technologies PHP PHP Programs PHP-date-time date-time-program +1 More Similar Reads PHP Programs PHP Programs is a collection of coding examples and practical exercises designed to help beginners and experienced developers. This collection covers a wide range of questions based on Array, Stirng, Date, Files, ..., etc. Each programming example includes multiple approaches to solve the problem.Wh 7 min read PHP Basic ProgramsDifferent ways to write a PHP codeThe full form of PHP is a Hypertext preprocessor. It was developed by Rasmus Lerdorf. It is a programming language for developing dynamic web applications and interactive websites. It is a server-side scripting language. It is used for establishing a connection between the front-end and database i.e 2 min read How to write comments in PHP ?Comments are non-executable lines of text in the code that are ignored by the PHP interpreter. Comments are an essential part of any programming language. It help developers to understand the code, provide explanations, and make the codebase more maintainable. Types of Comments in PHPPHP supports tw 1 min read Introduction to Codeignitor (PHP)Codeignitor is one of the popular MVC framework of PHP. 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Input : c:/xampp/htdocs/project/home Output : "" Input : c:/xampp/htdocs/project/index.php Output : ".php" Input : c:/xampp/htdocs/project/style.min.css Output : ".css" Using $_SERVER[‘SCRIPT_NAME’]: $_SERVER is an array o 2 min read Build a Grocery Store Web App using PHP with MySQLIn this article, we are going to build a Grocery Store Web Application using PHP with MySQL. In this application, we can add grocery items by their name, quantity, status (pending, bought, not available), and date. We can view, delete and update those items. There will be a date filtering feature wh 7 min read How to delete text from file using preg_replace() function in PHP ?Given a file containing some elements and the task is to delete the content of the file using preg_replace() function. The preg_replace() function is searches the string pattern in the file and if string pattern found then it replace with the required string. 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This process allows you to represent dates and times as strings in various formats, such as Y-m-d H:i:s. There are some following approachesTable of ContentB 4 min read How to get Time Difference in Minutes in PHP ?In this article, we will learn how to get time difference in minutes using PHP. We will be using the built-in function date_diff() to get the time difference in minutes. For this, we will be needed a start date and end date to calculate their time difference in minutes using the date_diff() function 3 min read Return all dates between two dates in an array in PHPReturning all dates between two dates in an array means generating a list of all consecutive dates from the start date to the end date, inclusive, and storing each date as an element in an array for easy access.Here we have some common methods:Table of ContentUsing DatePeriod ClassUsing strtotime() 4 min read Sort an array of dates in PHPWe are given an array of multiple dates in (Y-m-d) format. We have to write a program in PHP to sort all the dates in the array in decreasing order. Examples : Input : array("2018-06-04", "2014-06-08", "2018-06-05") Output : 2018-06-05 2018-06-04 2014-06-08 Input : array("2016-09-12", "2009-09-08", 2 min read Return all dates between two dates in an array in PHPReturning all dates between two dates in an array means generating a list of all consecutive dates from the start date to the end date, inclusive, and storing each date as an element in an array for easy access.Here we have some common methods:Table of ContentUsing DatePeriod ClassUsing strtotime() 4 min read How to convert a Date into Timestamp using PHP ?The Task is to convert a Date to a timestamp using PHP. The task can be done by using the strtotime() function in PHP. It is used to convert English textual date-time description to a UNIX timestamp. The UNIX timestamp represents the number of seconds between a particular date and the Unix Epoch. Sy 1 min read How to Add 24 Hours to a Unix Timestamp in PHP?The Unix Timestamp is designed to track time as a running total of seconds from the Unix Epoch on January 1st, 1970 at UTC. To add 24 hours to a Unix timestamp we can use any of these methods: Approach 1: Direct Addition of SecondsConvert 24 hours to seconds and add the result to the current Unix ti 2 min read Sort a multidimensional array by date element in PHPSorting a multidimensional array by element containing date. Use the usort() function to sort the array. The usort() function is PHP builtin function that sorts a given array using user-defined comparison function. This function assigns new integral keys starting from zero to array elements. Syntax: 2 min read Convert timestamp to readable date/time in PHPProblem: Convert timestamp to readable date/time in PHP Solution: This can be achieved with the help of date() function, which is an inbuilt function in PHP can be used to format the timestamp given by time() function. This function returns a string formatted according to the given format string usi 1 min read PHP | Number of week days between two datesYou are given two string (dd-mm-yyyy) representing two date, you have to find number of all weekdays present in between given dates.(both inclusive) Examples: Input : startDate = "01-01-2018" endDate = "01-03-2018" Output : Array ( [Monday] => 9 [Tuesday] => 9 [Wednesday] => 9 [Thursday] = 2 min read PHP | Converting string to Date and DateTimeConverting the string to Date and DateTime uses several functions/methods like strtotime(), getDate(). We will see what these functions do. strtotime() This is basically a function which returns the number of seconds passed since Jan 1, 1970, just like a linux machine timestamp. It returns the numbe 2 min read How to get last day of a month from date in PHP ?Given a date and the task is to print the last day of the month. We will use date() and strtotime() function to get the last day of the month. Used PHP functions:date() function: Format a local time/date.strtotime() function: Parse about any English textual datetime description into a Unix timestamp 2 min read PHP String ProgramsPHP Change strings in an array to uppercaseChanging strings in an array to uppercase means converting all the string elements within the array to their uppercase equivalents. This transformation modifies the array so that every string, regardless of its original case, becomes fully capitalized.Examples:Input : arr[] = ("geeks", "For", "GEEks 3 min read How to convert first character of all the words uppercase using PHP ?To convert the first character of all the words present in a string to uppercase, we just need to use one PHP function i.e. ucwords().ucwords(string,delimiters)This function takes 2 parameters. The first one is the string which is mandatory. The second parameter is the delimiter. Example 1:PHP<?p 2 min read How to get the last character of a string in PHP ?In this article, we will find the last character of a string in PHP. The last character can be found using the following methods.Using array() Method: In this method, we will find the length of the string, then print the value of (length-1). For example, if the string is "Akshit" Its length is 6, in 2 min read How to convert uppercase string to lowercase using PHP ?Converting an uppercase string to lowercase means changing all capital letters in the string to their corresponding small letters. This is typically done using programming functions or methods to ensure uniformity in text formatting and comparison.Below we have some common approaches Table of Conten 2 min read How to extract Numbers From a String in PHP ?Extracting numbers from a string involves identifying and isolating numerical values embedded within a text. This process can be done using programming techniques, such as regular expressions, to filter out and retrieve only the digits from the string, ignoring all other characters.Here we have some 3 min read How to replace String in PHP ?Replacing a string in PHP involves substituting parts of a string with another string. Common methods include str_replace() for simple replacements, preg_replace() for pattern-based replacements, substr_replace() for positional replacements, and str_ireplace() for case-insensitive replacements. Each 2 min read How to Encrypt and Decrypt a PHP String ?In PHP, Encryption and Decryption of a string is possible using one of the Cryptography Extensions called OpenSSL function for encrypt and decrypt. openssl_encrypt() Function: The openssl_encrypt() function is used to encrypt the data. Syntax: string openssl_encrypt( string $data, string $method, st 4 min read How to display string values within a table using PHP ?A table is an arrangement of data in rows and columns, or possibly in a more complex structure. Tables are widely used in communication, research, and data analysis. Tables are useful for various tasks such as presenting text information and numerical data.Tables can be used to compare two or more i 1 min read How to write Multi-Line Strings in PHP ?Multi-Line Strings can be written in PHP using the following ways.Using escape sequencesWe can use the \n escape sequences to declare multiple lines in a string.PHP Code:PHP<?php //declaring multiple lines using the new line escape sequence $var="Geeks\nFor\nGeeks"; echo $var; ?>Output:Geeks F 2 min read How to check if a String Contains a Substring in PHP ?Checking whether a string contains a specific substring is a common task in PHP. Whether you're parsing user input, filtering content, or building search functionality, substring checking plays a crucial role.MethodsBelow are the following methods by which we can check if a string contains a substri 1 min read How to append a string in PHP ?We have given two strings and the task is to append a string str1 with another string str2 in PHP. There is no specific function to append a string in PHP. In order to do this task, we have the this operator in PHP:Table of ContentUsing Concatenation assignment operator (".=")Using Concatenation Ope 3 min read How to remove white spaces only beginning/end of a string using PHP ?We have given a string and the task is to remove white space only from the beginning of a string or the end from a string str in PHP. In order to do this task, we have the following methods in PHP:Table of ContentUsing ltrim() MethodUsing rtrim() MethodUsing a Custom Regular Expression with preg_rep 3 min read How to Remove Special Character from String in PHP?We are given a string and the task is to remove special characters from string str in PHP.Below are the approaches to remove special characters from string in PHP:Table of ContentUsing str_replace() MethodUsing str_ireplace() MethodUsing preg_replace() MethodUsing str_replace() MethodThe str_replace 2 min read How to create a string by joining the array elements using PHP ?We have given an array containing some array elements and the task is to join all the array elements to make a string. In order to do this task, we have the following methods in PHP:Table of ContentUsing implode() Method: Using join() MethodUsing array_reduce()Using a Foreach LoopUsing array_map() w 3 min read How to prepend a string in PHP?We have given two strings and the task is to prepend a string str1 with another string str2 in PHP. There is no specific function to prepend a string in PHP. To do this task, we have the following operators in PHP:Below are the methods to prepend a string in PHPTable of ContentUsing Concatenation Op 2 min read How to replace a word inside a string in PHP ?Given a string containing some words the task is to replace all the occurrences of a word within the given string str in PHP. To do this task, we have the following methods in PHP:Table of ContentUsing str_replace() MethodUsing str_ireplace() Method Using preg_replace() MethodUsing strtr()Using preg 4 min read How to remove all white spaces from a string in PHP ?Given a string element containing some spaces and the task is to remove all the spaces from the given string str in PHP. In order to do this task, we have the following methods in PHP:Table of ContentUsing str_replace() MethodUsing str_ireplace() MethodUsing preg_replace() MethodUsing explode() and 4 min read How to count the number of words in a string in PHP ?Given a string containing some words and the task is to count number of words in a string str in PHP. In order to do this task, we have the following approaches:Table of ContentUsing str_word_count() MethodUsing trim(), preg_replace(), count() and explode() method. Using trim(), substr_count(), and 4 min read How to find number of characters in a string in PHP ?We have given a string and the task is to count number of characters in a string str in PHP. In order to do this task, we have the following methods in PHP:Table of ContentMethod 1: Using strlen() MethodMethod 2: Using mb_strlen() MethodMethod 3: Using iconv_strlen() MethodMethod 4: Using grapheme_s 3 min read How to get a substring between two strings in PHP?To get a substring between two strings there are few popular ways to do so. Below the procedures are explained with the example.Examples: Input:$string="hey, How are you?"If we need to extract the substring between "How" and "you" then the output should be are Output:"Are"Input:Hey, Welcome to Geeks 4 min read How to get a variable name as a string in PHP?Use variable name as a string to get the variable name. There are many ways to solve this problem some of them are discussed below: Table of ContentUsing $GLOBALSUsing $$ OperatorUsing debug_backtrace()Using get_defined_vars() and array_search()Method 1: Using $GLOBALS: It is used to reference all v 3 min read Removing occurrences of a specific character from end of a string in PHPThere is a lot of options to remove all specific characters at the end of a string. Some of them are discussed below:Using rtrim() functionThis function is an inbuilt function in PHP that removes whitespaces or other characters (if specified) from the right side of the string.Syntax:rtrim( $string, 3 min read How to convert string to boolean in PHP?Given a string and the task is to convert given string to its boolean. Use filter_var() function to convert string to boolean value. Examples: Input : $boolStrVar1 = filter_var('true', FILTER_VALIDATE_BOOLEAN); Output : true Input : $boolStrVar5 = filter_var('false', FILTER_VALIDATE_BOOLEAN); Output 2 min read Generating Random String Using PHPGenerating a random string involves creating a sequence of characters where each character is selected unpredictably from a defined set (e.g., letters, numbers, symbols). This process is used in programming to produce unique identifiers, passwords, tokens, or keys for security and randomness in appl 2 min read How to generate a random, unique, alphanumeric string in PHPThere are many ways to generate a random, unique, alphanumeric string in PHP which are given below: Table of ContentUsing str_shuffle() FunctionUsing md5() FunctionUsing sha1() FunctionUsing random_bytes() FunctionUsing random_int() in a Custom FunctionUsing uniqid() with more_entropy parameterUsing 4 min read Remove new lines from string in PHPGiven a multiple line sentence or statement the task is to convert the whole statement in a single line. See the example below. Examples: Input : Hello welcome to geeksforgeeks.Output : Hello welcome to geeksforgeeks.Remove the new line between Hello and geeksforgeeks.Input : I love geeksforgeeksOut 2 min read Insert string at specified position in PHPGiven a sentence, a string and the position, the task is to insert the given string at the specified position. We will start counting the position from zero. See the examples below. Input : sentence = 'I am happy today.' string = 'very' position = 4 Output :I am very happy today.Input : sentence = ' 3 min read PHP Program to check a string is a rotation of another stringGiven the two strings we have to check if one string is a rotation of another string. Examples: Input : $string1 = "WayToCrack", $string2 = "CrackWayTo"; Output : Yes Input : $string1 = "WillPower" $string2 = "lliW"; Output : No. The above problem can be easily solved in other languages by concatena 3 min read PHP Classes ProgramsPHP Access ModifiersIn object-oriented programming, access specifiers are also known as access modifiers. These specifiers control how and where the properties or methods of a class can be accessed, either from inside the class, from a subclass, or from outside the class. PHP supports three primary access specifiers: p 4 min read PHP | Constructors and DestructorsIn PHP, constructors and destructors are special methods that are used in object-oriented programming (OOP). They help initialize objects when they are created and clean up resources when the object is no longer needed. These methods are part of the class lifecycle.In this article, we will discuss w 5 min read PHP | Type Casting and Conversion of an Object to an Object of other classGiven a PHP class object and the task is to convert or cast this object into object of another class. Approach 1: Objects which are instances of a standard pre-defined class can be converted into object of another standard class. Example: php <?php // PHP program to show // standard type casting 3 min read PHP | Type Casting and Conversion of an Object to an Object of other classGiven a PHP class object and the task is to convert or cast this object into object of another class. Approach 1: Objects which are instances of a standard pre-defined class can be converted into object of another standard class. Example: php <?php // PHP program to show // standard type casting 3 min read How to merge two PHP objects?Merging two PHP objects means combining their properties and values into a single object. This is typically done by copying the properties from one object to another, ensuring that both objects' data are preserved in the resulting merged object without overwriting critical values.Here we have some c 2 min read Abstract Classes in PHPAbstract classes in PHP are classes that may contain at least one abstract method. Unlike C++, abstract classes in PHP are declared using the abstract keyword. The purpose of abstract classes is to enforce that all derived classes implement the abstract methods declared in the parent class. An abstr 2 min read PHP JSON ProgramsHow to parse a JSON File in PHP?Parsing JSON in PHP is simple and efficient. JSON (JavaScript Object Notation) is a lightweight format used to store data in key-value pairs. PHP offers built-in functions to handle JSON encoding and decoding, making it easy to work with JSON data.JSON Syntax OverviewThe general syntax of a JSON obj 3 min read How to generate Json File in PHP ?In this article, we are going to generate a JSON file in PHP by using an array. JSON stands for JavaScript object notation, which is used for storing and exchanging data. JSON is text, written with JavaScript object notation. Structure: {"data":[ { "sub_data1":"value1", "sub_data2":"value2","sub_dat 3 min read How to Convert JSON file into CSV in PHP ?In this article, we are going to see how to convert JSON data into a CSV file using PHP. JSON (JavaScript Object Notation) is a dictionary-like notation that can be used to structuring data. It is stored with the extension .json, for example - geeksforgeeks.json On the other hand, CSV (or Comma Sepa 2 min read How to Convert XML data into JSON using PHP ?In this article, we are going to see how to convert XML data into JSON format using PHP. Requirements: XAMPP Server Introduction: PHP stands for hypertext preprocessor, which is used to create dynamic web pages. It also parses the XML and JSON data. XML stands for an extensible markup language in wh 3 min read How to Insert JSON data into MySQL database using PHP?To insert JSON data into MySQL database using PHP, use the json_decode function in PHP to convert JSON object into an array that can be inserted into the database. Here, we are going to see how to insert JSON data into MySQL database using PHP through the XAMPP server in a step-by-step way. JSON Str 3 min read How to convert PHP array to JavaScript or JSON ?PHP provides a json_encode() function that converts PHP arrays into JavaScript. Technically, it is in JSON format. JSON stands for JavaScript Object Notation. Statement: If you have a PHP array and you need to convert it into the JavaScript array so there is a function provided by PHP that will easi 2 min read How to receive JSON POST with PHP ?In this article, we will see how to retrieve the JSON POST with PHP, & will also see their implementation through the examples. First, we will look for the below 3 features: php://input: This is a read-only stream that allows us to read raw data from the request body. It returns all the raw data 2 min read How to use cURL to Get JSON Data and Decode JSON Data in PHP ?In this article, we are going to see how to use cURL to Get JSON data and Decode JSON data in PHP.cURL: It stands for Client URL.It is a command line tool for sending and getting files using URL syntax.cURL allows communicating with other servers using HTTP, FTP, Telnet, and more.Approach:We are goi 2 min read PHP File Systems ProgramsHow to Create a Folder if It Doesn't Exist in PHP ?We can easily create a folder in PHP, but before that, you have to check if the folder or directory already exists or not. So In this article, you will learn both to Check and Create a folder or directory in PHP. Methods: file_exists(): It is an inbuilt function that is used to check whether a file 3 min read How to check if File Exists in PHP ?To check whether any file is existing or not then we can use the below-mentioned PHP function. To find the existence of the files, we use file_exists() function. This function is used to check whether a file or directory exists or not. Syntax: file_exists( $path ) Parameters: This function accept on 1 min read How to write Into a File in PHP ?In this article, we are going to discuss how to write into a text file using the PHP built-in fwrite() function. The fwrite() function is used to write into the given file. It stops at the end of the file or when it reaches the specified length passed as a parameter, whichever comes first. The file 2 min read Deleting all files from a folder using PHPIn PHP, files from a folder can be deleted using various approaches and inbuilt methods such as unlink, DirectoryIterator and DirectoryRecursiveIterator. Some of these approaches are explained below: Approach 1: Generate a list of files using glob() method Iterate over the list of files. Check wheth 3 min read How to get file name from a path in PHP ?In this article, we will see how to get the file name from the path in PHP, along with understanding its implementation through the examples. We have given the full path & we need to find the file name from the file path. For this, we will following below 2 methods: Using the basename() function 2 min read How to Log Errors and Warnings into a File in PHP?In PHP, errors and warnings can be logged into a file by using a PHP script and changing the configuration of the php.ini file. Two such approaches are mentioned below: Approach 1: Using error_log() FunctionThe error_log() function can be used to send error messages to a given file. The first argume 3 min read How to extract extension from a filename using PHP ?In this article, we will see how to extract the filename extension in PHP, along with understanding their implementation through the examples. There are a few different ways to extract the extension from a filename with PHP, which is given below: Using pathinfo() function: This function returns info 2 min read How to get names of all the subfolders and files present in a directory using PHP?Given the path of the folder and the task is to print the names of subfolders and files present inside them. Explanation: In our PHP code, initially, it is checked whether provided path or filename is a directory or not using the is_dir() function. Now, we open the directory using opendir() function 2 min read Like