Please note that the web version of this document is optimized for Microsoft’s Internet Explorer. If you do not have IE, you may download this zipped file containing the text document and associated graphics. (Of course, you’ll have to learn how to unzip it first!)
For a number of people these days, the Internet is quickly overtaking standard mail as a way of transferring information. For example, attached to an e-mail might be files containing pictures, pieces of music, spreadsheets, word processing documents, etc., etc. In fact, nearly any item that can be recorded in “computer” (i.e. digitized) form can also be transferred to another person or place via e-mail or FTP.
Two common difficulties encountered by people who use this method are:
Compressing files is also a great way of archiving your files for posterity. For example, supposing that you had just finished a grueling creative-writing course in which you were writing several short essays a week. By the end of the year you may have accumulated well over a hundred essays. You are so sick of essays that you never want to see them again. Yet you still recognize that they are worth keeping. An easy option is to compress all of your essays into a single ZIP file. Not only does this get rid of the multitude of separate files residing on your hard drive, but it also compresses their size to a fraction of their original sum-total.
As a result, numerous software publishers have published various compression programs which address both of these issues. Perhaps the most common compression format is the ZIP format. You can tell that a file is a zipped file by the ZIP extension at the end of the filename. While we will only be addressing ZIP files in this document, you should also recognize that files ending in TAR, GZIP, ARJ, ARC, to name a few, are all archives of compressed files.
Let’s take as an example a file called: vacation_pictures.zip . The ZIP extension informs us that this is an archive of multiple files. Suppose that this file contains 35 scanned photographs of somebody’s vacation. Yet by compressing them, we condense all of them into one single file. (This is much easier than attaching 35 different files to an e-mail!) Further, the size of the zipped file may be considerably smaller than the sum of the size of the individual pictures. That is, suppose that each image is 100 K in size, the sum total should be 3500K (3.5 megs). However, you may* find that the zipped file is only 1 meg in size.
If you were to e-mail this vacation_pictures.zip file to a friend, all they would have to do is possess an “unzip” program and they would then find all 35 pictures on their hard drive, ready for viewing.
When I teach programming courses, students are now required to submit their assignments via e-mail. For some projects, students may find that they have anywhere from 5 to 15 separate files to send. By zipping them up, they can then attach just the one file making it easier on both the students and resulting in a happier grader (who has less downloading to do).
Even if I haven’t convinced you yet of a personal need for becoming familiar with archived files, any significant work using the Internet and your computer will soon force the issue. The reason is that many (probably most) software programs that are available for download over the Internet are available only in zipped format. Therefore, you must know how to uncompress these files before you can install the application.
Okay, so hopefully I’ve convinced or frightened you into committing to learning to use a compression/expansion utility. The most common one around is Winzip, available for downloading from http://www.winzip.com . This program will enable you to unzip (expand) archived files, and to create archives of your own.
When you run Winzip (I am using version 7.0) you are faced with the following
The ‘New’ button is used when you want to create a new archive. The ‘Open’ button is used to expand (or “collapse”) an existing archive. We will first focus on collapsing a pre-existing archive.
Suppose that somebody has just handed me a floppy disk containing a file called ‘phone.zip’. The zip extension tells me that this is an archived file. So I open up Winzip and then click on the ‘Open’ button. I am then prompted with a standard windows dialogue box prompting me for the file. I navigate** to A:\ and select the file ‘phone.zip’. When I do, I see the following:
These 8 files are the ones that were collectively enclosed in the ‘phone.zip’ archive. Notice that there are HTML files, text files, and even an Access database, all present inside that one archive!
However, I’m not done yet. The next step is to ‘Extract’ the files. In other words, all the above screen did was show us the files that were contained in the archive. We now need to expand them to their original size.
This too is not a complicated procedure. All we need to do is click on the ‘Extract’ button .
Winzip says, “Okay, but where do you want me to put all these files?” So we provide a location as shown here:
In the above dialogue, I told Winzip to place all of the extracted files into c:\temp\phone. (Note that even if this directory did not exist previously, Winzip would have created it for me).
That’s it! Now all these files are ready and waiting for me in the c:\temp\phone directory.
I click on the ‘New’ button and see the following:
Winzip is prompting me to name my archive (even before putting anything inside!). Because I am going to condense several pictures from the ‘France 95’ directory, I name the archive ‘france_pics’. Winzip will automatically append the ZIP extension onto the filename. Note that the ‘france_pics.zip’ file is going to be placed in the ‘1pic’ directory.
I am taken to the following dialogue:
Now suppose that I only want to place 5 images in my archive. To do so I hold down the CONTROL button on my keyboard, and click on the files I wish to add. Try it—you’ll see that it works! (By the way, this is an extremely useful Windows shortcut when dealing with files). I then click on ‘Add’.
And that too is it!! You will then see the following window:
This window shows us the files that were added to the archive. Notice that the name of the archive is at the top of the window.
But just so that you don’t take my word for it, here’s a snapshot of my ‘1pic’ directory after the archival procedure:
Notice the ‘france_pics.zip’ file at the bottom.
When you install Winzip, the application adds an option to your right mouse-click button. If you go to Windows Explorer and select multiple files and then right click, you will see the option of ‘Add to Zip’.
This is a quick and easy way of creating a new archive.
So as with nearly all other things involving computers, the best way to familiarize yourself with the application is to get out there and play with it. In fact, you can practice by downloading an archive containing this presentation (i.e. all of the images and the DOC file) in Microsoft Word format. Good luck!
* Note the liberal use of the qualifier “may”. The amount of compression depends on the kinds of files being compressed. If you are adding previously compressed files (such as JPGs) to your archive, you will see little or no additional compression from Winzip. However, you will still gain the advantage of collapsing multiple files into one single file-name.
** Click here for a tutorial on navigating and using files and directories.