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PHP Articles
Page 62 of 81
Compare define() vs const in PHP
In PHP, both define() and const are used to declare constants, but they have important differences in when and how they can be used. Syntax FOO BAR Key Differences Compile-time vs Runtime Definition The basic difference is that const defines constants at compile time, whereas define() defines them at run time ? Available immediately Available after execution Conditional Definition We can't use const in conditional blocks, while define() allows conditional constant declaration ? This ...
Read MoreHow to call parent constructor in child class in PHP?
In PHP object-oriented programming, there are two scenarios when calling parent constructors in child classes, depending on whether the child class defines its own constructor. Case 1: Child Class Has Its Own Constructor When a child class defines its own constructor, the parent constructor is not automatically called. You must explicitly call parent::__construct() within the child constructor to execute the parent's initialization code ? I am in Tutorials Point I am not in Tutorials Point Explanation In the above example, parent::__construct() explicitly calls the parent class constructor before executing ...
Read MoreHow to Check if PHP session has already started?
In PHP, we utilize session_start() to start a session. However, calling this function multiple times in the same script throws an error. Here we will learn how to check if a session has already started without calling session_start() twice. There are two methods to resolve this problem, depending on your PHP version. Method 1: Using session_id() (PHP < 5.4.0) For PHP versions below 5.4.0, use the session_id() function to check if a session exists − The session_id() function returns an empty string if no session has been started, making it perfect for ...
Read MoreWhat is Pass By Reference and Pass By Value in PHP?
In PHP, you can pass arguments to functions using two methods: pass by value (default) and pass by reference. Understanding the difference is crucial for effective programming. By default, PHP uses pass by value, meaning the function receives a copy of the variable. Changes inside the function don't affect the original variable. However, pass by reference allows the function to modify the original variable by using the ampersand (&) symbol. Pass By Reference To pass a variable by reference, prepend an ampersand (&) to the parameter name in the function definition. This allows the function to modify ...
Read MoreWhat are getters and setters methods in PHP?
In this article, we learn the best way to create getter and setter methods in PHP. Getter and setter methods are utilized when we need to restrict direct access to variables by end−users. Getters and setters are methods used to define or retrieve the values of variables, normally private ones. Just as the name suggests, a getter method is a technique that gets or recovers the value of an object. Also, a setter method is a technique that sets the value of an object. Why Use Private Properties? Let's first understand why direct access to private properties ...
Read MoreExplain Polymorphism in PHP.
Polymorphism is derived from the Greek words "Poly" (meaning many) and "morphism" (meaning forms). In object-oriented programming, polymorphism allows methods in different classes that perform similar functions to share the same interface, enabling code to work with objects of different classes through a common interface. In PHP, polymorphism is implemented using interfaces or abstract classes. This ensures that different classes can be used interchangeably as long as they implement the same contract. Using Interfaces for Polymorphism An interface defines method signatures without implementation. Classes that implement an interface must provide implementations for all methods declared in the ...
Read MoreWhat is method overloading in PHP?
Method overloading is a concept in Object Oriented Programming that allows creating multiple methods with the same name that behave differently based on the number or type of parameters they accept. While traditional method overloading (static polymorphism) isn't directly supported in PHP, we can achieve similar functionality using PHP's magic methods. Traditional Method Overloading Issue Unlike other programming languages, PHP doesn't support traditional method overloading. The following example demonstrates this limitation ? Fatal error: Cannot redeclare machine::doTask() This error occurs because PHP treats both methods as duplicate declarations, regardless of ...
Read MoreExplain include(),require(),include_once() and require_once() functions in PHP.
In PHP, file inclusion functions allow you to incorporate external PHP files into your current script. The four main functions − include(), require(), include_once(), and require_once() − serve similar purposes but differ in their error handling and inclusion behavior. include() The include() function includes a specified file. If the file is not found, it generates a warning but continues script execution ? require_once() The require_once() function combines the behavior of require() and the "once" feature. It includes a file only once and generates a fatal error if missing ?
Read MoreConvert object to an array in PHP.
In PHP applications, we often work with data in various formats such as strings, arrays, and objects. Sometimes we need to convert a PHP object to an associative array to process the data more efficiently or to make it compatible with certain functions. An object is an instance of a class that has properties and methods, while an associative array uses string keys to store key−value pairs. Converting objects to arrays allows easier data manipulation and serialization. Using json_encode() and json_decode() The json_encode() function converts a PHP value to JSON string, and json_decode() converts it back to ...
Read MoreComparison of floating point values in PHP.
In PHP, testing floating point values for equality is problematic because of how floating point numbers are represented internally. Values that appear identical may not actually be equal due to precision limitations. This article demonstrates the issue and provides solutions for reliable floating point comparison. The Problem Let's examine this issue with a simple example − a and b are not same The else condition executes even though both variables should equal 0.14. This occurs because floating point arithmetic can introduce tiny rounding errors that make direct equality comparison unreliable. ...
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