-C LANGUAGE-
AN INTRODUCTION TO HYPERTEXT MARK-UP LANGUAGE (HTML)
Hypertext Mark-up Language is a series of tags added to plain text which make documents available to the World Wide Web and control elements of their appearance. A working knowledge of basic HTML will allow anyone to become an on-line publisher. HTML gives an author the ability to include graphics, to manipulate text, and to format a document. It also lets both the author and the viewer follow trains of thought through the use of "hot links" which connect to text, concepts, or resources in other documents.
The World Wide Web is the most recent in a long line of Internet tools. It operates on the basis of a "client/server" relationship. Without having to know much about the technical aspects of the operation, a user is able to locate and retrieve information made available by a provider and stored as a system of files on a server. The server is a computer connected to the network and running the appropriate software to allow for the necessary behind-the-scenes functions to occur. The server acts as a file archive. It stores files, sits and listens for requests from the network, and then it locates the requested documents and negotiates the transfer of data to the client. The server does not check for accuracy of content, accuracy of HTML, or control any aspect of the document’s display.
The client is the receiving end of the transaction. It will employ some kind of browser software, such as Internet Explorer, Netscape, or Lynx (text only) to interpret the source document and carry out the details of the transfer and display. The client makes the request to the server, retrieves the information and then exhibits the result. The display is the most important of the client’s responsibilities. The client will select fonts, colors, and other attributes of a document’s display. Client requests are addressed via a Uniform Resource Locator (URL). The URL might be thought of as somewhat analogous to a street address, and the method of conveyance used to get there. When someone asks for your URL they want to know where the files that comprise your web site reside. The URL consists of the method by which your documents are to be accessed, the domain name of the server where they are stored, and the pathname to a particular file in a particular directory.
HTML is not a programming language. The HTML documents are plain text. Tags are a series of directives added to the text of a source document. The tags are visible in the source document, but invisible to the viewer using a browser, and instead are interpreted by the client, resulting in the display being seen in a particular fashion. All HTML tags are enclosed within left and right angle brackets ( "<" and ">") to indicate their special function. The tags instruct the client to display a special characteristic implied by the tag (such as a bold typeface, italic type, or perhaps the inclusion of a graphic or a link). The syntax would appear this way in source document:
<b>text to be bolded</b>
Most tags come in pairs, a closing tag being the correspondent to the opening tag. You turn an attribute on <b> and then turn it off </b>. Not all tags require closing, however. The tags for including images, horizontal rules, and line breaks, for instance, are all "stand alone".
A template document containing basic HTML tags may be created then copied later and added to as necessary to create particular pages. A very basic template should look something like this:
<html>
<head>
<title> </title>
</head>
<body>
</body>
</html>
When displayed by the client, all the "action" will take place in the area in between <body> and </body> tags. When designing the web page, that is the part of the source document that will contain the text and the attribute tags that make up the web page as a viewer sees it.
The server does not control the display of the document. The client is almost always responsible for formatting lines of text. Two different browsers may display the same source document in very different ways. The final display can also differ somewhat from the source document. For instance, the browser will ignore extra spaces between words; (including tabs, new lines, etc.) even though they can be seen in the source document. This takes some time to get accustomed to when learning HTML. You can force line breaks and paragraph spacing by inserting appropriate tags. <br> forces a line break and <p> causes double spacing to occur between paragraphs.
By default the typeface and font are assigned by the client. Style tags can modify font sizes, and some typefaces. All style tags are paired. The opening tag indicates the starting point of where the displayed text is to be altered and the closing tag indicates the end to that portion of the text. The basic style tags are:
<b>bold </b> - bold
<I>italics</I> - italics
<tt>typewriter text</tt> -
typewriter textThere are also tags which allow for superscript, subscript, and strikeout. The tags are not case sensitive, meaning that they can be placed in the source document in either upper case (capital) letters or lower case letters.
Headers are achieved by using the following tags:
<h1>Largest</h1>
Largest<h2> </h2>
<h3> </h3>
<h4> </h4>
<h5> </h5>
<h6>Smallest</h6>
SmallestWhen you use a Header tag the enclosed text is automatically bolded, and double spacing occurs immediately afterward. Using the <font> tag will also allow for altering the size of the enclosed text as it is displayed, but will not bold or double space after the tag is closed. The syntax would look like this:
<font size=+3>Some text</font> -
Some text - Other values will result in other sizes<
font color=#ff0000>Some text</font> - Changes text to red - Other values will result in other colorsThe size and color attributes can also be combined in one tag, which is turned off with one </font> tag.
Links are the bits of text that generally appear as blue and underlined when viewed with a browser, and allow the viewer to click on that text with the mouse and be transferred automatically to another document. In some cases a link will go to another piece of text in the same document. The HTML behind a link looks something like this:
<a href="http://www.yahoo.com">link text</a>
It is telling the browser that it wants to use "link text" as an anchor <a> and that the action performed should link the anchor to a particular URL via a hypertext reference <href> and that it should use hypertext transfer protocol <http> to accomplish it. It also says that the anchor is closed after the word "text" and that any subsequent text will be plain, and not part of the link.
Images work in a similar fashion. At the point where the author wishes an in-line image to appear in the final document a tag should be placed in the source document that looks like this:
<img src="somefile.gif">
In this case, the .gif file would have to reside in the same directory on the server as the source document. The <img> tag always refers to an actual .gif or .jpg file and the source must always point to where the file resides.
Data can be organized in a number of ways, primarily through the use of Lists and Tables. This document will not delve into an explanation of the logistics of either, but merely inform the reader of the existence of these options. Lists can be used to emphasize points through the use of indention and the inclusion of numbers or bullets along side the items being. Tables are used to arrange pieces of information within a framework that can be either visible or invisible to the viewer.
Two of the most important things to consider when actually designing your new web page are: who your audience will be and how to keep things simple. Always keep in mind that not everyone is using the latest version of a particular browser, and may in fact be viewing the page as text-only. You don’t want to be boring, but using all the latest bells and whistles is generally only entertaining to someone visiting your page for the first time. After that, things like blinking text or large, slow-loading graphics can become more an annoyance. You can think outside the lines of traditional publishing, however. Remember that HTML will support audio and video files, and animated graphics. As long as you don’t go overboard with these features they can greatly enhance the information you are putting forward.
It might be wise to do some research before you begin to design your pages. Take a look at what other entities such as your own have done with regard to the World Wide Web and make note of things you find appealing about their pages and then incorporate some of them into your layout. Be careful with your color selections. Don’t use large areas of bright colors next to one another unless you are intending to create a particular effect. Spread things out around the page, and use devices like color and size to draw attention to pertinent areas of text.
Be creative and have fun. Once you have even a basic understanding of HTML you can create web pages that are entertaining and informative, and have the potential of reaching a wide audience.
C was developed at Bell Laboratories in 1972 by Dennis Ritchie. Many of its principles and ideas were taken from the earlier language B and B's earlier ancestors BCPL and CPL. CPL ( Combined Programming Language ) was developed with the purpose of creating a language that was capable of both high level, machine independent programming and would still allow the programmer to control the behavior of individual bits of information. The one major drawback of CPL was that it was too large for use in many applications. In 1967, BCPL ( Basic CPL ) was created as a scaled down version of CPL while still retaining its basic features. In 1970, Ken Thompson, while working at Bell Labs, took this process further by developing the B language. B was a scaled down version of BCPL written specifically for use in systems programming. Finally in 1972, a co-worker of Ken Thompson, Dennis Ritchie, returned some of the generality found in BCPL to the B language in the process of developing the language we now know as C.
C's power and flexibility soon became apparent. Because of this, the Unix operating system which was originally written in assembly language, was almost immediately re-written in C ( only the assembly language code needed to "bootstrap" the C code was kept ). During the rest of the 1970's, C spread throughout many colleges and universities because of it's close ties to Unix and the availability of C compilers. Soon, many different organizations began using their own versions of C causing compatibility problems. In response to this in 1983, the American National Standards Institute ( ANSI ) formed a committee to establish a standard definition of C which became known as ANSI Standard C. Today C is in widespread use with a rich standard library of functions.
C is a powerful, flexible language that provides fast program execution and imposes few constraints on the programmer. It allows low level access to information and commands while still retaining the portability and syntax of a high level language. These qualities make it a useful language for both systems programming and general purpose programs.
C's power and fast program execution come from it's ability to access low level commands, similar to assembly language, but with high level syntax. It's flexibility comes from the many ways the programmer has to accomplish the same tasks. C includes bitwise operators along with powerful pointer manipulation capabilities. C imposes few constraints on the programmer. The main area this shows up is in C's lack of type checking. This can be a powerful advantage to an experienced programmer but a dangerous disadvantage to a novice.
Another strong point of C is it's use of modularity. Sections of code can be stored in libraries for re-use in future programs. This concept of modularity also helps with C's portability and execution speed. The core C language leaves out many features included in the core of other languages. These functions are instead stored in the C Standard Library where they can be called on when needed.. An example of this concept would be C's lack of built in I/O capabilities. I/O functions tend to slow down program execution and also be machine independent when running optimally. For these reasons, they are stored in a library separately from the C language and only included when necessary.