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In this Guide, Kai Chandler looks at WinZip
Practical PC often receives emails from readers asking - "What is WinZip and do I need it?"
This Computing Guide introduces file compression and how to use WinZip, the most popular compression tool.
First, why would anyone want to make files smaller? The three main reasons are:
- To reduce the time taken to download the file or to email it.
- To reduce the space taken up on a drive
- To keep a set of files together for distribution, for example, of a shareware program
The reductions in size are quite impressive. As an example, a screen dump saved as a .bmp file occupies 2.25MB. I know because I just made one, of this page. The same file after compression occupies only 54.1kB - that's a ratio of 42:1. This compression is completely loss-less. That is to say that if you expand the compressed file, you will end up with the 2.25MB file once again.
Although you can compress any sort of file including images, sound, executables, documents and even compressed files, they will not all compress to the same extent - paradoxically if you compress a file that is already compressed, it may become slightly larger!
If it sounds like magic - we ought to spare a moment to see how it works - imagine a photograph of a beach scene with lots of blue sky. The image is stored on the computer as a set of pixels or data elements - if there are 500 of these each representing a sky-blue colour, then it's more efficient to store a specification that says 'sky-blue times 500' than to specify each colour individually.
As you might expect, there are dozens of different compression formats that have been developed over the years, but the most common is the zipfile or .zip.
One of the most popular compression and decompression programs is WinZip.
In use, WinZip is very straightforward:
To expand a file eg. <yourfile.zip>
- Select the file in Windows Explorer or My Computer
- Doubleclick it
- The file is opened in WinZip from where you can install the program or extract the file(s).
Icons allow you to
- extract the files to a folder of your choice,
- view the files without removing them from the archive,
- install a program - this is very useful if you have downloaded a shareware program from Practical PC's download area
- run a wizard which will prompt you every step of the way
Another way to expand a zipfile is to start WinZip and then select the Open icon.
Winzip is able to expand dozens of different file formats - full details are in WinZip's help file.
You can open files within the archive by doubleclicking them. The files will be opened with any associated application. For example, Word documents will be opened in Word if installed. A range of options appears if you rightclick one or more files.
To create a .zip file eg. <newfile.zip>
There are several ways to create a zip file: the easiest is from Windows Explorer or My Computer.
- Select the file(s) using Windows Explorer or My Computer that you wish to compress
- Right click on the file(s) to display a set of options including 'Add to Zip'
- Select 'Add to Zip'
- The Add window appears with a suggested path or location for the archive. Change it as you need. The 'Multiple disk spanning' field is only selectable if you are saving to removable media such as a floppy disk drive.
- Select Add to create your .zip archive.
Other ways to use WinZip to create archive files are to use the New icon in Winzip and then select the files to include drag files from Windows Explorer or My Computer to the WinZip icon on your desktop created during installation.
The Add window includes a range of choices of which the Action drop down list is the most useful as it allows you to choose whether to Add files, or Freshen them. Freshening is replacing the files in the archive with more up to date files. The Move option works the same as Add, except that once the specified files have been added to the archive they are deleted from disk.
When creating files, WinZip supports automatic disk spanning - this means that if the target disk becomes full, WinZip will prompt you to insert another disk. You can easily save files to floppy disk that are several times larger than the disk itself. WinZip can add a password but be careful because it's not difficult to find a shareware cracking program to hack into a password protected file.
So to sum up, we hope we have answered the question of "What is WinZip and do I need it?" Download it now and find out for yourself how useful it is. Note that WinZip is shareware - that means you can download it for free and evaluate it - in this case for up to 21 days. A registration fee of $29 is required if you use it after the 21 day evaluation period. Full details of how to register are included with the program.
If you are unsure how to download and install a program then please refer to our earlier guide.
If you want to read more about compression then Iain Laskey's PPC Guide to Compression is essential reading!
