C A High Level Programming Language example essay topic

IT RELATED TERMS UNIX A high-level programming language developed by Dennis Ritchie at Bell Labs in the mid 1970's. Although originally designed as a systems programming language, C has proved to be a powerful and flexible language that can be used for a variety of applications, from business programs to engineering. C is a particularly popular language for personal computer programmers because it is relatively small - it requires less memory than other languages. The first major program written in C was the UNIX operating system, and for many years C was considered to be inextricably linked with UNIX.

Now, however, C is an important language independent of UNIX. Although it is a high-level language, C is much closer to assembly language than are most other high-level languages. This closeness to the underlying machine language allows C programmers to write very efficient code. The low-level nature of C, however, can make the language difficult to use for some types of applications. LINUX Pronounced lee-necks, A freely-distributable implementation of UNIX that runs on a number of hardware platforms, including Intel and Motorola microprocessors. It was developed mainly by Linus Torvalds.

Because it's free, and because it runs on many platforms, including PCs, Macintosh es and Amigas, Linux has become extremely popular over the last couple years. Another popular, free version of UNIX that runs on Intel microprocessors is FreeBSD. GUI A program interface that takes advantage of the computer's graphics capabilities to make the program easier to use. Well-designed graphical user interfaces can free the user from learning complex command languages.

On the other hand, many users find that they work more effectively with a command-driven interface, especially if they already know the command language. Graphical user interfaces, such as Microsoft Windows an the one used by the Apple Macintosh, feature the following basic components: pointer: A symbol that appears on the display screen and that you move to select objects and commands. Usually, the pointer appears as a small angled arrow. Text -processing applications, however, use an I-beam pointer that is shaped like a capital I. pointing device: A device, such as a mouse or trackball, that enables you to select objects on the display screen. icons: Small pictures that represent commands, files, or windows. By moving the pointer to the icon and pressing a mouse button, you can execute a command or convert the icon into a window. You can also move the icons around the display screen as if they were real objects on your desk. desktop: The area on the display screen where icons are grouped is often referred to as the desktop because the icons are intended to represent real objects on a real desktop. windows: You can divide the screen into different areas.

In each window, you can run a different program or display a different file. You can move windows around the display screen, and change their shape and size at will. menus: Most graphical user interfaces let you execute commands by selecting a choice from a menu. The first graphical user interface was designed by Xerox Corporation's Palo Alto Research Center in the 1970's, but it was not until the 1980's and the emergence of the Apple Macintosh that graphical user interfaces became popular. One reason for their slow acceptance was the fact that they require considerable CPU power and a high-quality monitor, which until recently were prohibitively expensive. In addition to their visual components, graphical user interfaces also make it easier to move data from one application to another. A true GUI includes standard formats for representing text and graphics.

Because the formats are well-defined, different programs that run under a common GUI can share data. This makes it possible, for example, to copy a graph created by a spreadsheet program into a document created by a word processor. Many DOS programs include some features of GUIs, such as menus, but are not graphics based. Such interfaces are sometimes called graphical character-based user interfaces to distinguish them from true GUIs. MULTITASKING The ability to execute more than one task at the same time, a task being a program. The terms multitasking and multiprocessing are often used interchangeably, although multiprocessing sometimes implies that more than one CPU is involved.

In multitasking, only one CPU is involved, but it switches from one program to another so quickly that it gives the appearance of executing all of the programs at the same time. There are two basic types of multitasking: preemptive and cooperative. In preemptive multitasking, the operating system parcels out CPU time slices to each program. In cooperative multitasking, each program can control the CPU for as long as it needs it. If a program is not using the CPU, however, it can allow another program to use it temporarily. OS/2, Windows 95, Windows NT, the Amiga operating system and UNIX use preemptive multitasking, whereas Microsoft Windows 3. x and the Multi Finder (for Macintosh computers) use cooperative multitasking.

OS/2 An operating system for PCs developed originally by Microsoft Corporation and IBM, but sold and managed solely by IBM. OS/2 is compatible with DOS and Windows, which means that it can run all DOS and Windows programs. However, programs written specifically to run under OS/2 will not run under DOS or Windows. Since its introduction in the late 80's, OS/2 has traveled a particularly rocky road. The first releases were hampered by a number of technical and marketing problems. Then Microsoft abandoned the project in favor of its own operating system solution, Microsoft Windows.

That break spawned a feud between the two computer giants that is still being played out in many arenas. ASSEMBLY LANGUAGE A programming language that is once removed from a computer's machine language. Machine languages consist entirely of numbers and are almost impossible for humans to read and write. Assembly languages have the same structure and set of commands as machine languages, but they enable a programmer to use names instead of numbers. Each type of CPU has its own machine language and assembly language, so an assembly language program written for one type of CPU won't run on another. In the early days of programming, all programs were written in assembly language.

Now, most programs are written in a high-level language such as FORTRAN or C. Programmers still use assembly language when speed is essential or when they need to perform an operation that isn't possible in a high-level language. C# A hybrid of C and C++, it is Microsoft's newest programming language developed to compete with Sun's Java language. C# is an object-oriented programming language used with XML -based Web services on the. NET platform and designed for improving productivity in the development of Web applications. C# boasts type-safety, garbage collection, simplified type declarations, versioning and scalability support, and other features that make developing solutions faster and easier, especially for COM+ and Web services. Microsoft critics have pointed to the similarities between C# and Java.

C++ A high-level programming language developed by Bjarne Stroustrup at Bell Labs. C++ adds object-oriented features to its predecessor, C. C++ is one of the most popular programming language for graphical applications, such as those that run in Windows and Macintosh environments. HIGH LEVEL LANGUAGES A programming language such as C, FORTRAN, or Pascal that enables a programmer to write programs that are more or less independent of a particular type of computer. Such languages are considered high-level because they are closer to human languages and further from machine languages. In contrast, assembly languages are considered low-level because they are very close to machine languages. The main advantage of high-level languages over low-level languages is that they are easier to read, write, and maintain.

Ultimately, programs written in a high-level language must be translated into machine language by a compiler or interpreter. The first high-level programming languages were designed in the 1950's. Now there are dozens of different languages, including Ada, Algol, BASIC, COBOL, C, C++, FORTRAN, LISP, Pascal, and Prolog. LOW LEVEL LANG The lowest-level programming language (except for computers that utilize programmable microcode) Machine languages are the only languages understood by computers.

While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers. Programmers, therefore, use either a high-level programming language or an assembly language. An assembly language contains the same instructions as a machine language, but the instructions and variables have names instead of being just numbers. Programs written in high-level languages are translated into assembly language or machine language by a compiler. Assembly language programs are translated into machine language by a program called an assembler. Every CPU has its own unique machine language.

Programs must be rewritten or recompiled, therefore, to run on different types of computers. PROG LANG A vocabulary and set of grammatical rules for instructing a computer to perform specific tasks. The term programming language usually refers to high-level languages, such as BASIC, C, C++, COBOL, FORTRAN, Ada, and Pascal. Each language has a unique set of keywords (words that it understands) and a special syntax for organizing program instructions. High-level programming languages, while simple compared to human languages, are more complex than the languages the computer actually understands, called machine languages. Each different type of CPU has its own unique machine language.

Lying between machine languages and high-level languages are languages called assembly languages. Assembly languages are similar to machine languages, but they are much easier to program in because they allow a programmer to substitute names for numbers. Machine languages consist of numbers only. Lying above high-level languages are languages called fourth-generation languages (usually abbreviated 4 GL). 4 GLs are far removed from machine languages and represent the class of computer languages closest to human languages. your program into machine language so that the computer can understand it. There are two ways to do this: compile the program interpret the program See compile and interpreter for more information about these two methods.

The question of which language is best is one that consumes a lot of time and energy among computer professionals. Every language has its strengths and weaknesses. For example, FORTRAN is a particularly good language for processing numerical data, but it does not lend itself very well to organizing large programs. Pascal is very good for writing well-structured and readable programs, but it is not as flexible as the C programming language. C++ embodies powerful object-oriented features, but it is complex and difficult to learn.

The choice of which language to use depends on the type of computer the program is to run on, what sort of program it is, and the expertise of the programmer. V C++ An application development tool developed by Microsoft for C++ programmers. Visual C++ supports object-oriented programming of 32-bit Windows applications with an integrated development environment (IDE), a C / C++ compiler, and a class library called the Microsoft Foundation Classes (MFC). The IDE includes an App Wizard, Class Wizard, and testing features to make programming easier. Visual C++ was introduced in 1993, and Release 4.0 became available in 1996. MFC Short for Microsoft Foundation Classes, a large library of C++ classes developed by Microsoft.

For Windows -based applications written in C++, MFC provides an enormous headstart. One of the hardest parts of developing C++ programs is designing a logical hierarchy of classes. With MFC, this work has already been done. MFC is bundled with several C++ compilers and is also available as part of the Microsoft Developer's Network (MSDN)...

Object-oriented programming (OOP) A popular buzzword that can mean different things depending on how it is being used. Object-oriented programming (OOP) refers to a special type of programming that combines data structures with functions to create re-usable objects (see under object-oriented programming). Object-oriented graphics is the same as vector graphics. Otherwise, the term object-oriented is generally used to describe a system that deals primarily with different types of objects, and where the actions you can take depend on what type of object you are manipulating. For example an object-oriented draw program might enable you to draw many types of objects, such as circles, rectangles, triangles, etc. Applying the same action to each of these objects, however, would produce different results.

If the action is Make 3 D, for instance, the result would be a sphere, box, and pyramid, respectively. BASIC Acronym for Beginner's All-purpose Symbolic Instruction Code. Developed by John Keeney and Thomas Kurtz in the mid 1960's at Dartmouth College, BASIC is one of the earliest and simplest high-level programming languages. During the 1970's, it was the principal programming language taught to students, and continues to be a popular choice among educators. Despite its simplicity, BASIC is used for a wide variety of business applications. There is an ANSI standard for the BASIC language, but most versions of BASIC include many proprietary extensions.

Microsoft's popular Visual Basic, for example, adds many object-oriented features to the standard BASIC. Recently, many variations of BASIC have appeared as programming, or macro, languages within applications. For example, Microsoft Word and Excel both come with a version of BASIC with which users can write programs to customize and automate these applications. CLASS In object-oriented programming, a category of objects. For example, there might be a class called shape that contains objects which are circles, rectangles, and triangles. The class defines all the common properties of the different objects that belong to it.

VB A programming language and environment developed by Microsoft. Based on the BASIC language, Visual Basic was one of the first products to provide a graphical programming environment and a paint metaphor for developing user interfaces. Instead of worrying about syntax details, the Visual Basic programmer can add a substantial amount of code simply by dragging and dropping controls, such as buttons and dialog boxes, and then defining their appearance and behavior. Although not a true object-oriented programming language in the strictest sense, Visual Basic nevertheless has an object-oriented philosophy. It is sometimes called an event-driven language because each object can react to different events such as a mouse click. Since its launch in 1990, the Visual Basic approach has become the norm for programming languages.

Now there are visual environments for many programming languages, including C, C++, Pascal, and Java. Visual Basic is sometimes called a Rapid Application Development (RAD) system because it enables programmers to quickly build prototype applications. JAVA A high-level programming language developed by Sun Microsystems. Java was originally called OAK, and was designed for handheld devices and set-top boxes. Oak was unsuccessful so in 1995 Sun changed the name to Java and modified the language to take advantage of the burgeoning World Wide Web. Java is an object-oriented language similar to C++, but simplified to eliminate language features that cause common programming errors.

Java source code files (files with a. java extension) are compiled into a format called bytecode (files with a. class extension), which can then be executed by a Java interpreter. Compiled Java code can run on most computers because Java interpreters and runtime environments, known as Java Virtual Machines (VMs), exist for most operating systems, including UNIX, the Macintosh OS, and Windows. Bytecode can also be converted directly into machine language instructions by a just-in-time compiler (JIT). Java is a general purpose programming language with a number of features that make the language well suited for use on the World Wide Web. Small Java applications are called Java applets and can be downloaded from a Web server and run on your computer by a Java-compatible Web browser, such as Netscape Navigator or Microsoft Internet Explorer. IFC Short for Internet Foundation Classes, a set of Java classes developed by Netscape that enables programmers to easily add GUI elements, such as windows, menus and buttons.

Netscape and Sun Microsystems have announced that the next version of the Java Development Kit (JDK) will combine the Abstract window Toolkit (AWT) with the IFC. This combination of classes will be called the Java Foundation Classes (JFC). The IFC is similar to Microsoft's Application Foundation Classes (AFC). AWT Short for Abstract Windows Toolkit, the Java API that enables programmers to develop Java applications with GUI components, such as windows, buttons, and scroll bars. The Java Virtual Machine (VM) is responsible for translating the AWT calls into the appropriate calls to the host operating system. Ideally, the AWT should enable any Java application to appear the same whether it's run in a Windows, Macintosh or UNIX environment.

In practice, however, most Java applications look slightly different depending on the platform on which they " re executed. POLYMORPHISM Generally, the ability to appear in many forms. In object-oriented programming, polymorphism refers to a programming language's ability to process objects differently depending on their data type or class. More specifically, it is the ability to redefine methods for derived classes. For example, given a base class shape, polymorphism enables the programmer to define different circumference methods for any number of derived classes, such as circles, rectangles and triangles. No matter what shape an object is, applying the circumference method to it will return the correct results.

Polymorphism is considered to be a requirement of any true object-oriented programming language (OOP). The type of polymorphism described above is sometimes called parametric polymorphism to distinguish it from another type of polymorphism called overloading. NET WORK MANAGEMENT Refers to the broad subject of managing computer networks. There exists a wide variety of software and hardware products that help network system administrators manage a network. Network management covers a wide area, including: Security: Ensuring that the network is protected from unauthorized users. Performance: Eliminating bottlenecks in the network.

Reliability: Making sure the network is available to users and responding to hardware and software malfunctions. ACTIVE WEB PAGE 1. A specification for a dynamically created Web page with a. ASP extension that utilizes ActiveX scripting - usually VB Script or Jscript code. When a browser requests an ASP page, the Web server generates a page with HTML code and sends it back to the browser. So ASP pages are similar to CGI scripts, but they enable Visual Basic programmers to work with familiar tools.

2. ASP also stands for Application Service Provider VB SCRIPT Short for Visual Basic Scripting Edition, a scripting language developed by Microsoft and supported by Microsoft's Internet Explorer Web browser. VBScript is based on the Visual Basic programming language, but is much simpler. In many ways, it is similar to JavaScript. It enables Web authors to include interactive controls, such as buttons and scrollbars, on their Web pages. VIRTUAL MACHINE A self-contained operating environment that behaves as if it is a separate computer.

For example, Java applets run in a Java virtual machine (VM) that has no access to the host operating system. This design has two advantages: System Independence: A Java application will run the same in any Java VM, regardless of the hardware and software underlying the system. Security: Because the VM has no contact with the operating system, there is little possibility of a Java program damaging other files or applications. The second advantage, however, has a downside. Because programs running in a VM are separate from the operating system, they cannot take advantage of special operating system features. JAVA BEANS A specification developed by Sun Microsystems that defines how Java objects interact.

An object that conforms to this specification is called a Javabeans, and is similar to an ActiveX control. It can be used by any application that understands the JavaBeans format. The principal difference between ActiveX controls and JavaBeans are that ActiveX controls can be developed in any programming language but executed only on a Windows platform, whereas JavaBeans can be developed only in Java, but can run on any platform. DATA TYPE In programming, classification of a particular type of information. It is easy for humans to distinguish between different types of data.

We can usually tell at a glance whether a number is a percentage, a time, or an amount of money. We do this through special symbols - %, : , and $ - that indicate the data's type. Similarly, a computer uses special internal codes to keep track of the different types of data it processes. Most programming languages require the programmer to declare the data type of every data object, and most database systems require the user to specify the type of each data field. The available data types vary from one programming language to another, and from one database application to another, but the following usually exist in one form or another: integer: In more common parlance, whole number; a number that has no fractional part. floating-point: A number with a decimal point. For example, 3 is an integer, but 3.5 is a floating-point number. character (text): Readable text ACTIVE XA control using ActiveX technologies.

An ActiveX control can be automatically downloaded and executed by a Web browser. ActiveX is not a programming language, but rather a set of rules for how applications should share information. Programmers can develop ActiveX controls in a variety of languages, including C, C++, Visual Basic, and Java. An ActiveX control is similar to a Java applet.

Unlike Java applets, however, ActiveX controls have full access to the Windows operating system. This gives them much more power than Java applets, but with this power comes a certain risk that the applet may damage software or data on your machine. To control this risk, Microsoft developed a registration system so that browsers can identify and authenticate an ActiveX control before downloading it. Another difference between Java applets and ActiveX controls is that Java applets can be written to run on all platforms, whereas ActiveX controls are currently limited to Windows environments. Related to ActiveX is a scripting language called VBScript that enables Web authors to embed interactive elements in HTML documents. Just as JavaScript is similar to Java, so VBScript is similar to Visual Basic.

Currently, Microsoft's Web browser, Internet Explorer, supports Java, JavaScript, and ActiveX, whereas Netscape's Navigator browsers support only Java and JavaScript, though plug-ins can enable support of VBScript and ActiveX. BROWSER Short for Web browser, a software application used to locate and display Web pages. The two most popular browsers are Netscape Navigator and Microsoft Internet Explorer. Both of these are graphical browsers, which means that they can display graphics as well as text. In addition, most modern browsers can present multimedia information, including sound and video, though they require plug-ins for some formats.

APPLICATION A program or group of programs designed for end users. Software can be divided into two general classes: systems software and applications software. Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources. In contrast, applications software (also called end-user programs) includes database programs, word processors, and spreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.