C++ Reference [C++ Reference] Codecademy Labs Polymorphism Before getting any deeper into this chapter, you should have a proper understanding of pointers and class inheritance. If you are not really sure of the meaning of any of the following expressions, you should review the indicated sections: Pointers to base class One of the key features of class inheritance is that a pointer to a derived class is type-compatible with a pointer to its base class. The example about the rectangle and triangle classes can be rewritten using pointers taking this feature into account: Function main declares two pointers to Polygon (named ppoly1 and ppoly2). Dereferencing ppoly1 and ppoly2 (with *ppoly1 and *ppoly2) is valid and allows us to access the members of their pointed objects. But because the type of ppoly1 and ppoly2 is pointer to Polygon (and not pointer to Rectangle nor pointer to Triangle), only the members inherited from Polygon can be accessed, and not those of the derived classes Rectangle and Triangle. Virtual members Abstract base classes
PHP Security Guide PHP Editor Review - Articles Sql Phpmyadmin Learning SQL Using phpMyAdmin Structured Query Language is a non-procedural language used to define, manipulate and retrieve data. It was developed by IBM (System/R project) in 1974-1979. The American National Standards Institute (ANSI) published in 1986 the first official standard of the language (later revised in 1989, 1992 and 1999), and since then, the industry has widely adopted SQL as the relational database language. Virtually every database system nowadays is interfaced through SQL. The specific data architecture addressed by SQL is called the relational architecture. In this article, we will use MySQL, a popular open-source implementation of SQL that is deployed by most Web host providers. To be able to do the exercises in this guide, you will need an access to a MySQL server. This guide will show you the SQL syntax, sometimes by asking you to enter statements, and sometimes by letting you see how phpMyAdmin generates SQL statements based on your actions using the interface. Joins
Build a CMS in an Afternoon with PHP and MySQL You're now ready to build the Article PHP class. This is the only class in our CMS, and it handles the nitty-gritty of storing articles in the database, as well as retrieving articles from the database. Once we've built this class, it will be really easy for our other CMS scripts to create, update, retrieve and delete articles. Inside your cms folder, create a classes folder. This file is quite long, but it's fairly simple stuff when you break it down. Everything after these lines of code — up until the closing brace at the end of the file — contains the code that makes up the Article class. After starting our class definition, we declare the properties of the class: $id, $publicationDate, and so on. Technically, this type of class — which contains properties that map directly to the corresponding database fields, as well as methods for storing and retrieving records from the database — follows an object-oriented design pattern known as active record. Next we create the class methods . . hi
The Basics of C Programming" The previous discussion becomes a little clearer if you understand how memory addresses work in a computer's hardware. If you have not read it already, now would be a good time to read How Bits and Bytes Work to fully understand bits, bytes and words. All computers have memory, also known as RAM (random access memory). For example, your computer might have 16 or 32 or 64 megabytes of RAM installed right now. RAM holds the programs that your computer is currently running along with the data they are currently manipulating (their variables and data structures). Memory can be thought of simply as an array of bytes. float f; This statement says, "Declare a location named f that can hold one floating point value." While you think of the variable f, the computer thinks of a specific address in memory (for example, 248,440). f = 3.14; The compiler might translate that into, "Load the value 3.14 into memory location 248,440." The output that you see from the program will probably look like this: