Tuesday, July 18, 2017
Encapsulation
Encapsulation is an Object Oriented Programming concept that binds together the data and functions that manipulate the data, and that keeps both safe from outside interference and misuse. Data encapsulation led to the important OOP concept of data hiding.
If a class does not allow calling code to access internal object data and permits access through methods only, this is a strong form of abstraction or information hiding known asencapsulation. Some languages (Java, for example) let classes enforce access restrictions explicitly, for example denoting internal data with the
private keyword and designating methods intended for use by code outside the class with the public keyword. Methods may also be designed public, private, or intermediate levels such asprotected (which allows access from the same class and its subclasses, but not objects of a different class). In other languages (like Python) this is enforced only by convention (for example, private methods may have names that start with an underscore). Encapsulation prevents external code from being concerned with the internal workings of an object. This facilitates code refactoring, for example allowing the author of the class to change how objects of that class represent their data internally without changing any external code (as long as "public" method calls work the same way). It also encourages programmers to put all the code that is concerned with a certain set of data in the same class, which organizes it for easy comprehension by other programmers. Encapsulation is a technique that encourages decoupling.
Sunday, July 16, 2017
History of the web browser
A web browser is a software application for retrieving, presenting and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier (URI) and may be a web page, image, video, or other piece of content.Hyperlinks present in resources enable users easily to navigate their browsers to related resources. A web browser can also be defined as an application software or program designed to enable users to access, retrieve and view documents and other resources on the Internet.
Precursors to the web browser emerged in the form of hyperlinked applications during the mid and late 1980s, and following these, Tim Berners-Lee is credited with developing in 1990 both the first web server, and the first web browser, called WorldWideWeb (no spaces) and later renamed Nexus. Many others were soon developed, with Marc Andreessen's 1993 Mosaic (later Netscape), being particularly easy to use and install, and often credited with sparking the internet boom of the 1990s.Today, the major web browsers are Microsoft Edge, Firefox, Internet Explorer, Google Chrome, Opera, and Safari.
The explosion in popularity of the Web was triggered in September 1993 by NCSA Mosaic, a graphical browser which eventually ran on several popular office and home computers. This was the first web browser aiming to bring multimedia content to non-technical users, and therefore included images and text on the same page, unlike previous browser designs;[7] its founder, Marc Andreessen, also established the company that in 1994, released Netscape Navigator, which resulted in one of the early browser wars, when it ended up in a competition for dominance (which it lost) with Microsoft's Internet Explorer (for Windows).
Friday, July 14, 2017
Computer graphics
Computer graphics are pictures and films created using computers. Usually, the term refers to computer-generated image data created with help from
Some topics in computer graphics include user interface design, sprite graphics, vector graphics, 3D modeling, shaders, GPU design, implicit surface visualization with ray tracing, and computer vision, among others. The overall methodology depends heavily on the underlying sciences of geometry, optics, and physics.
Computer graphics is responsible for displaying art and image data effectively and meaningfully to the user. It is also used for processing image data received from the physical world. Computer graphic development has had a significant impact on many types of media and has revolutionized animation, movies, advertising, video games, and graphic design generally.
Computer data storage
Computer data storage, often called storage or memory, is a technology
The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy which puts fast but expensive and small storage options close to the CPU and slower but larger and cheaper options farther away. Generally the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage"; however, "memory" is sometimes also used when referring to persistent storage.
In the Von Neumann architecture, the CPU consists of two main parts: The control unit and the arithmetic logic unit (ALU). The former controls the flow of data between the CPU and memory, while the latter performs arithmetic and logical operations on data.
Monday, July 10, 2017
Website
A website is a collection of related web pages, including multimedia content, typically identified with a common domain name, and published on at least one web server. A website may be accessible via a public Internet Protocol (IP) network, such as the Internet, or a private local area network (LAN), by referencing a uniform resource locator (URL) that identifies the site.
Websites have many functions and can be used in various fashions; a website can be a personal website, a commercial website for a company, a government website or a non-profit organization website. Websites are typically dedicated to a particular topic or purpose, ranging from entertainment and social networking to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are typically a part of an intranet.
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