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Archiving programs Archive file MS DOS PKZIP and ARJ RAR archivers Windows WinRAR 2.5 archivers WinRAR features WinZip 7.0 Comparative test of performance and compression ratio of the most popular archivers (WINRAR, WINZIP, RAR).
Archiving programs and their characteristics

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Archiving programs
Created by various developers special programs to archive files. Some of them are distributed free of charge, some - on a commercial basis (for a fee), but most programs of this kind are distributed as "Shareware". those. they can be obtained free of charge, but if you want to use them permanently, you must send the specified (usually small, up to $50) reward to the authors or distributors. As a rule, programs for archiving files allow you to put copies of files on disk in compressed form into an archive file, extract files from an archive, view the contents of an archive, and so on. Different programs differ in the format of archive files, speed of work, the degree of compression of files when placed in an archive, and ease of use. The most common archiving programs have approximately the same capabilities and none of them is superior to others in all respects: some programs work faster, others provide a better degree of file compression. Even if we compare programs only in terms of compression ratio, there is no leader among them: different files compress better different programs. The principle of operation of archivers is based on the search for "redundant" information in a file and its subsequent encoding in order to obtain a minimum volume. The most well-known method of archiving files is to compress sequences of identical characters. For example, inside your file are sequences of bytes that are frequently repeated. Instead of storing each byte, the number of repeated characters and their position is fixed. For example, a file to be archived is 15 bytes long and consists of the following characters: B B B B B L L L L L A A A A A

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In hexadecimal system 42 42 42 42 42 4C 4C 4C 4C 4C 41 41 41 41 41 The archiver can represent this file in the following form (hexadecimal): 01 05 42 06 05 4C 0A 05 41 This means: from the first position the character " is repeated five times B", from position 6, the character "L" is repeated five times, and from position 11, the character "A" is repeated five times. To store a file in this form, only 9 bytes are required, which is 6 bytes less than the original one. The described method is simple and very effective way file compression. However, it does not provide much space savings if the text being processed contains a small number of repeating character sequences. A more sophisticated method of data compression, used in one form or another by almost any archiver, is the so-called optimal prefix code and, in particular, encoding with variable length characters (Huffman algorithm). A variable length code allows the most frequently occurring characters and groups of characters to be written in just a few bits, while rare characters and phrases will be written in longer bit strings. For example, in any English text, the letter E occurs more often than Z, and X and Q are among the least common. Thus, using a special lookup table, it is possible to encode each letter E with fewer bits and use a longer code for rarer letters.
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Popular archivers ARJ, PAK, PKZIP work on the basis of the Lempel-Ziv algorithm. These archivers are classified as adaptive dictionary encoders, in which text strings are replaced with pointers to identical strings that occur earlier in the text. For example, all the words in a book can be represented as page numbers and line numbers in a dictionary. the most important hallmark This algorithm is the use of grammatical analysis of the previous text with its arrangement into phrases that are recorded in the dictionary. Pointers allow you to link to any phrase in a fixed size window preceding the current phrase. If a match is found, the current phrase is replaced by a pointer to its previous counterpart. When archiving, as well as when compressing, the degree of compression of files is highly dependent on the file format. Graphic files such as TIFF and GIF are already pre-compressed (although there is a variant of the TIFF format without compression) and here even the best archiver will find little to pack. A completely different picture is observed when archiving text files, *.BMP files and the like. All programs for archiving can be conditionally divided into two categories: For command line MS-DOS (ARJ, PKZIP, RAR, etc.) For WINDOWS OS (WINZIP, WINRAR, etc.)
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archive file
An archive file is a set of one or more files compressed into a single file, from which they can be extracted in their original form if necessary. The archive file contains a table of contents that allows you to find out which files are contained in the archive. The following information is stored in the archive's table of contents for each file it contains: file name; information about the directory that contains the file; date and time of the last modification of the file; file size on disk and in the archive; a loopback code for each file used to check the integrity of the archive; You can determine with which program a particular archive file was archived using the extension. For example: game.rar - archived using the RAR archiver. game.arj - archived using the ARJ archiver. game.zip - archived using a ZIP archiver. The question involuntarily arises why there are so many archivers and all for one purpose only - to compress the file size. Different programs differ in the format of archive files, speed of work, the degree of compression of files when placed in an archive, and ease of use.
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MS DOS archivers
With the development of the computer, the amount of information stored in it began to increase, which in turn led to the development of technologies for storing this information in a compressed form, that is, in archives. To do this, a lot of programs were invented for archiving information. However, when working with this information, it is sometimes undesirable to open the full archive in order to take one or two required files, or simply to see what kind of information is in the archive. Archiving programs, with the exception of a few, do not provide convenient shells that allow you to easily, quickly and visually deal with the contents of archives. The most famous archiving programs for MS-DOS: ARJ (developer - Robert K. Jung), PKZIP (PKWARE Inc.), IHA (Haruyasu Yoshizaki), ZOO (Rahul Dhesi). The undisputed leader in the world over the past 5 years has become the RAR archiver. Currently, RAR is actively replacing ZIP as the main utility for compressing FTP archives on the INTERNET. RAR is the only worldwide used program created by a Russian programmer (with the exception of TETRIS). All archivers differ in the compression algorithms used, archive file formats, speed, etc.
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PKZIP and ARJ
PKZIP Works from the command line. Various Functions for maintenance of zip archives are performed by different programs: pkzip - placing files in an archive pkunzip - extracting files from an archive zip2exe - creating a self-extracting archive pkzipfix - repairing a damaged archive. View help for working with the pkzip archiver using the following commands: pkzip /h pkunzip /h zip2exe /h ARJ Works from the command line. Performs all functions for maintaining .arj archives, incl. support for multi-volume archives. Arj has a very large number of keys. Many actions can be automated - creating a disk backup, archiving starting from a certain date, adding the current date (arh970821.arj) to the archive name, archiving a file from a specific location, several compression levels, and so on. In version 2.55 it is possible to work with long names. Advantages: a very large number of keys, which makes it possible to automate a large number of functions. Protection of the archive from damage. Disadvantages: the lack of an interactive mode, some inconvenience in the presence of some key in environment variable(ARJ_SW) and the launch line - mutual destruction.
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RAR
1. Introduction The RAR archiver was created as a fairly versatile tool for compressing files containing the most various information, which combines the advantages and conveniences of programs of two classes of a command line archiver and a full-screen shell for viewing and other manipulations with archives. In some cases, the use of RAR cannot be replaced by any of the existing archivers, and the logical and simple interface makes it a convenient tool for working with archives. In terms of its technical characteristics, RAR is not inferior to widespread and popular archivers, and in some respects it surpasses them. 2. Specifications 2.1. Compression ratio On files like .EXE, .COM, .LIB, .OBJ, .OVR and similar RAR, as a rule, provides the maximum compression ratio compared to other archivers, surpassing them by about 0.5 - 3% On individual files (large .LIB , some others) the gain can reach 5-7% of the packaged size. The compression method usually does not significantly affect the result. Text information is compressed approximately at the level of other archivers (depending on the type of text and compression method) on files up to 32 kilobytes in size. On large text files, RAR generally outperforms most other archivers. When packing database files, the compression method (m0 - m5) can significantly affect the size and operation time. Compression ratio graphic information strongly depends on the kind of files. When creating a continuous (solid) archive containing many small files of the same type, the compression ratio is 10 - 40% or more higher than that achieved when packing into a regular archive
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2.2. Additional features In addition to the standard functions, RAR provides a full-screen interface: selection of packed and unpacked files; emulation of the structure of subdirectories in the archive; work with the "mouse"; saving parameters in a configuration file; viewing packed and regular files in text or hexadecimal form. Special functions: splitting the archive into parts (volumes) for transferring to floppy disks; creation and modification of self-extracting archives (SFX); creation of self-extracting archive volumes (SFX); creation of continuous (solid) archives with a high degree of compression; protection of information by passwords; protection of archives from modification; saving information about the archive author; restoring the structure of damaged archives; adding comments to the entire archive and to individual files; native support for ANSI escape sequences in the comments. Working with ZIP, ARJ, LZH archives in full-screen mode: selecting files to be packed and unpacked emulating the structure of subdirectories in an archive performing basic operations on archives
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3.Working with RAR from the command line 3.1. Call format: rar - - There can be only one command, any number of keys. The list file may contain the names of the files to be processed, separated by a carriage return or a space. A file with a comment may contain a comment that is added to the archive when it is created, but not when it is modified. The decompression path, used together with the "e" and "x" commands, indicates the subdirectory where the decompressed files will be placed. If this subdirectory does not exist, it will be created. 3.2. Description of commands a: adds specified files to archive m: Transfers the specified files and subdirectories to the archive. Upon successful completion of packing, all specified files and subdirectories are removed from the disk. Removal of subdirectories will be performed only if the -ed switch was not used, and *.* or the name of the subdirectory was specified as the name of the added files. mf: transfers the specified files to the archive. If the package is successfully completed, all specified files are removed from the disk. d: removes the specified files from the archive: extracts the specified files from the archive, restoring the subdirectory structure (if the -r switch was specified during archiving). e: extracts the specified files from the archive into the current subdirectory v: view the contents of the archive. The full path to the file and its name, file comment, unpacked and packed size, packing degree, date and time of the last modification of the file, its attributes, checksum, compression method and the minimum RAR version required for unpacking are given. If you need to view all archive volumes (volumes), then the name of the archive is replaced with *.

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Windows does not have built-in functions for working with packed archives, so most users have to get special utilities and at the same time solve the problem of the diversity of archival formats. Capacity of magnetic disks and random access memory is constantly growing, data transmission channels are becoming more powerful, and yet the amount of information transmitted and stored is still a very significant factor that forces us to use software to work with packed data.
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WINDOWS archivers

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The WinRAR utility, developed by Russian programmer Evgeny Roshal, allows you to work with ZIP archives, but the main format for it is RAR (also developed by Roshal). In addition, it is possible to create self-extracting EXE archives, as well as use external programs for unpacking and viewing archives such as ARJ, LZH and CAB. The program creates multi-volume archives only in RAR format.
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WinRAR 2.5

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The RAR format outperforms ZIP, ARJ, and LZH in terms of compression efficiency, but the greatest advantage of this technology is in the case of "continuous" archives, which do not allow changes and are processed quite slowly. The WinRAR distribution kit is an EXE file of about 650 KB, after installation the package takes up almost 1.5 MB. There are versions of the archiver in English and Russian. The archiver window reminds system utility"My Computer", archives look and behave like normal folders. You can replenish archives and extract objects from them using drag and drop. To view packed files, the program has a built-in visualization module, but you can also connect an external viewing utility. The program is equipped with a very comprehensive help system. E. Roshal's utility is compact, convenient, quite versatile, its price is not as attractive as that of WinZip, but less than that of other leaders in this review - ZIP Explorer Pro and Zip Magic, so WinRAR may be the best choice for many. WinRAR is the 32-bit version of the popular RAR archiver for Windows, a powerful archive creation and management tool.
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WinRAR features:
full support for RAR and ZIP archives; original highly efficient data compression algorithm; special multimedia compression algorithm; shell with support for drag & drop technology; command line interface; management of archives of other formats (CAB, ARJ, LZH, TAR, GZ, ACE, UUE); support for solid archives, in which the compression ratio can be 10 - 50% higher than with conventional compression methods, especially when packing a significant number of small similar files; support for multi-volume archives; creation of self-extracting (SFX) regular and multi-volume archives using standard or additional SFX modules; recovery of physically damaged archives; other additional functions such as encryption, adding archive comments (supporting ANSI ESC sequences), error logging, etc.
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WinZip 7.0
Introduction. A shareware utility developed by Nico Mak Computing is probably the most famous backup program for Windows. The EXE file with the WinZip distribution takes about 940 KB; after installation, the volume of the program files is 2 MB. The program has built-in tools for manipulating archives and packed files in ZIP, TAR, GZIP and CAB formats, and also allows you to connect external modules to work with ARJ-, ARC- and LZH-files. All operations with archives can be performed using drag and drop, long object names (including Cyrillic ones) are processed normally.
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Working with the program Let's start with the most common scenario of working with the WinZip program. Let's say the directory XXXX contains files X1, X2, ..., Xn. They must be packed into a single archive. Find folder XXXX, select files X1, X2, ..., Xn (using left key mouse and Ctrl or Shift buttons). Then, after right-clicking with the mouse, select the Add to Zip command.
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Archive compression Word documents(doc or rtf) gives very significant disk space savings (up to 95%). A somewhat more modest result is achieved when compressing html files (up to 80%). It is more difficult with graphic files, bmp can be compressed up to 99%, but when archiving tif, jpg, gif, the savings will be up to 35, 25, 10%, respectively. However, when sending files by e-mail, it is necessary to take into account not only their physical size, but also their number, because it also takes time to process a request to send each file "attached" to a letter. The fact that so many recipients of your correspondence use all kinds of anti-virus programs and / or firewalls that can easily ignore any doc file because of its "suspiciousness" also speaks in favor of closing files with zip before sending them by e-mail, and the zip file is likely to slip through.
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When specifying the name of the archive file, the zip extension can be omitted, it is enough to enter only the name (in our case, "x") and click the Add button. The result is the appearance of the x.zip file in the XXXX folder (you could have specified another location)..

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Working interface
Through File, you can create a new one, open or close an archive, get to the table of favorite archives - Favorites (formed by the user), view the properties of the current zip file, put an icon with a link to it on the desktop, and also do anything with the archive itself (transfer , copy, rename, delete, print and link to email services). Those who like to go everywhere hand in hand with the "hint wizard" can select the Wizard mode (there is also a separate button). The Actions menu opens up a wide range of options (most of which are duplicated by special buttons): add (Add), delete (Delete), unpack (Extract), view individual files in the archive (View), select all files in the archive (Select All) and cancel this action (Ivert Selection). It is also possible to check the archived files for virus detection (Virus Scan) (of course, this requires that one of the antivirus programs). You can make an archive "self-extracting", that is, turning it into an executable exe file, by selecting the Make .Exe File command (control is passed to the WinZip Self-Extractor program). If at the same time you want to "spread" the self-extracting archive on floppy disks, select the Safe spanning method option. Among additional features this menu: converting the archive file to the universal UUE e-mail format, pre-checking the archive for unpacking, preparing a comment for the archive, creating a separate menu in the Start > Programs (CheckOut) section.
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Comparative test of performance and compression ratio of the most popular archivers (WINRAR, WINZIP, RAR).
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Archivers Compression time (in sec.) Final volume Compression ratio (in %)
WINRAR 851 276 MB (289,776,458 bytes) 97.08
WINZIP 59 276 MB (290 110 408 bytes) 97.19
RAR 245 167 MB (176,049,935 bytes) 58.98
Initial size 284 MB (298,502,392 bytes)

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Presentation on the topic: Archivers

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What are archivers? Archivers are one of the most common utility programs designed for archiving and packaging files by compressing information. An archive file is a specially organized file that contains one or more files in compressed or uncompressed form and service information (file names, date and time their creation, size, etc.)

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Information compression. Information compression is the process of converting information stored in a file to a form that reduces redundancy in its presentation and, accordingly, requires less memory for storage. Information is compressed by eliminating information redundancy. different ways, for example, by simplifying the codes, eliminating constant bits from them, or representing repeated characters as a repetition factor. Read more…

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Information compression. Information compression is the process of converting information stored in a file to a form that reduces redundancy in its representation and, accordingly, requires less memory for storage. Information is compressed by eliminating redundancy in various ways, for example, by simplifying codes, eliminating constant bits from them, or representations of repeated characters as a repetition factor. More... For example, if the word "mom" occurs 1000 times in a text file, then the size of the UNCOMPRESSED file is 4000 bytes (4 bytes x 1000 times = 4000 bytes). If this file is compressed, then the archiver will write the word "mother" to the archive only once, but at the same time note that this word occurs 4000 times. Thus our text file will shrink approximately 500 times.

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Information compression. The degree of information compression is one of the most important indicators of the archive. Characterized by the Kc coefficient, defined as the ratio of the volume of the compressed file Vc to the volume of the source file V0, expressed as a percentage (%). Files of executable programs (*.exe, *.com) and load modules (*.dll, for example) are poorly compressed - 60 -90%. Archive files are almost not compressed. Try to explain.

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Archivers. Archivers are programs that package and unpack files. Packing (archiving) - placing (loading) source files in compressed or uncompressed archive files. Unpacking (unzipping) - the process of restoring files from an archive exactly as they were before loading to the archive. When unpacking, files are extracted from the archive and placed on disk or in RAM. The most common archivers at present are:

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Archivers. Today, most users work with WinACE and WinRAR (the latter was developed in Russia). This is due to the fact that both of these archivers use better compression methods than WinZIP. In addition, they allow you to create self-extracting archives.

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winrar. The main features of the program: the ability to work in two modes - a full-screen interactive interface and a conventional command line interface; support for other types of archives (*.rar, *.arj), viewing their contents, changing and converting; compression by 10-50% more... the ability to create self-extracting and multi-volume archives protection of the archive from changes with a password (blocking) the ability to partially or completely restore damaged archives many other functions of the archiver (more than 15) can be found in the reference manual

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Self-extracting archives. Self-extracting archives is a bootable, executable module that is capable of independently unzipping the files contained in it without using an archiver program. Archiver programs allow you to create archive files that do not require any programs to extract, because. the archive files themselves may contain an unpacking program. Such files are called self-extracting archives. Most often, such archives have the *.exe extension. Such archives are called SFX archives (from SelF-eXtracting). This addition, called the SFX module, increases the size of the archive by 35 kilobytes. For comparison: a new formatted 3.5” floppy has 1400 kilobytes free.

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Multi-volume archives. One of the most important advantages of the WinRAR archiver is the ability to create multi-volume archives, i.e. archives that require two or more floppy disks. Each disk contains one or more volumes. Also, the ability to work with multi-volume archives can be useful when working on the Internet, more precisely when working with email, when there is a limit on the size of letters. A multi-volume archive is an archive “split” into a certain number of parts (volumes), whereby: the first volume of a multi-volume archive receives the extension *.rar, and the extensions of subsequent volumes are numbered as *.r00, *.r01, *.r02 etc. to *.r99

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Non-stop archive A non-stop archive is a RAR archive packaged in a special way, in which all compressed files are treated as one sequential data stream. Continuous archiving is only supported in the RAR format, there is no such type of archive for the ZIP format. The compression method for RAR archives - normal or continuous - is selected by the user. Continuous archiving significantly increases the compression ratio, especially when adding a significant number of small files with similar content to the archive. However, it should be kept in mind that continuous archiving also has some disadvantages: updating continuous archives (ie adding files to an existing archive or deleting them) is slower than regular ones; · To extract one file from a continuous archive, you have to analyze all the previous archived files, so extracting individual files from the middle of a continuous archive is slower than extracting from a regular archive. However, if all or several first files are extracted from a continuous archive, then in this case the unpacking speed is almost equal to the unpacking speed of a regular archive; · if any file in a continuous archive is damaged, then all the files following it will not be able to be extracted.

Archiving is the process of compressing one or more files in order to save memory and placing the compressed data in a single archive file.

Data archiving is a reduction in the physical size of the files in which data is stored, without significant information loss.

Archiving is carried out in the following cases:

- it is necessary to back up the most valuable files

- need to free up disk space

- need to transfer files Email

The main disadvantage archives is the impossibility of direct access to data. They must first be extracted from the archive or unpacked.

The unpacking operation, however, like packing, requires some system resources. This is not an instant operation. Therefore, archives are mainly used with relatively rare

Compression methods for archivers.

Run length coding(RLE is short for run - length encoding - run length encoding).

A consecutive series of identical data elements is replaced by two characters: the element and the number of its repetitions. Both an additional and an intermediate method are widely used. As an independent method, it is used, for example, in graphic format bmp.

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Suppose there is some piece of data:

A certain regularity is observed in the fragment. The sequence "110" is repeated four times in a row. Thus, it becomes possible to replace the above fragment with the following sequence:

KEY\repeat\repeat\repeat\

Where under the key section 110 is indicated, and the repeat symbol means that the same key as in the previous one should be in its place. If we conditionally say that the repetition is denoted as 1,

then the original fragment is converted to:

As a result, from a sequence of twelve bits, a sequence of six bits is obtained. That is, the application

encoding algorithm made it possible to compress the source file into two

Dictionary method (LZ - short for Lempel Ziv - authors' names).

The most common method. A dictionary is used, consisting of sequences of data or words. When compressed, these words are replaced by their dictionary codes. In the most common implementation, the original data block itself acts as a dictionary.

The main parameter of the dictionary method is the size of the dictionary. The larger the dictionary, the greater the efficiency. However, for heterogeneous data, an excessively large size can be harmful, since if the data type changes abruptly, the dictionary will be filled with irrelevant words. For effective work This method requires additional memory for compression. Approximately an order of magnitude more than needed for the original dictionary data. A significant advantage of the dictionary method

Entropy method(Huffman - Huffman coding, Arithmetic coding - arithmetic coding)

In this method, data elements that occur more often are encoded in compression with a shorter code, and rarer data elements are encoded with a longer code. Due to the fact that there are much more short codes, the total size is less than the original one.

Widely used as an additional method. As an independent method, it is used, for example, in the JPG graphic format.

Context modeling method(CM is short for context modeling).

In this method, a model of the initial data is built. When compressing the next data element, this model produces its prediction or probability. According to this probability, the data element is encoded by the entropy method. How more precisely the model will match the original data, the more accurately it will produce predictions, and the shorter the data elements will be encoded.

Building an efficient model requires a lot of memory. When unpacking, you have to build exactly the same model. Therefore, the speed and RAM requirements for packing and unpacking are almost the same. IN this moment context modeling methods provide the best compression ratio, but are extremely slow. PPM (PPM - Prediction by Partial Matching - prediction by

partial match).

A subspecies of contextual modeling. Prediction

performed on the basis of a certain number

Data Block Sorting Method(BWT - short for Burrows Wheeler Transform - named after the authors).

This is a special kind or group of transformations, in based on sorting. Almost any data can be subjected to such a transformation. Sorting is performed on blocks, so the data is pre-divided into parts. The main parameter is the size of the block being sorted. To unpack data, you need to do almost the same steps as when packing. Therefore, the speed and RAM requirements are almost the same. Archivers who use this method, usually show high speed and compression ratio for text data.

Preliminary transformations or filtering.

These methods are not used for compression, but for presenting information in a form convenient for further compression.

For example, uncompressed multimedia data is characterized by smooth changes signal level. Therefore, a delta conversion is used for them, when a relative value is taken instead of an absolute value.

There are filters for text, executable files, databases and others.

Segmentation.

This is a preliminary breakdown into homogeneous parts. These parts are then encoded individually or in groups.

There are a large number of compression methods. Each method is usually focused on one type or group of real data. Good results are shown by the complex use of methods.

Data features.

The compression ratio mainly depends on the source data.

Almost everything pre-compresses well

uncompressed data.

Uncompressed audio (WAV), complex uncompressed images (BMP) are compressed to a limited extent.

Almost all already compressed data is not compressed,

e.g. archives (ZIP , CAB), compressed documents (PDF),

compressed graphics and video (JPG, GIF, AVI, MPG), compressed audio

Archiving programs.

Archivers are programs (a set of programs) that compress and restore compressed files in their original form. The process of compressing files is called archiving. The process of recovering compressed files is by unzipping.

Modern archivers differ in algorithms used, speed, compression ratio (WinZip 9.0, WinAce 2.5, PowerArchiver 2003 v.8.70, 7Zip 3.13, WinRAR 3.30, WinRAR 3.70 RU).

Other names of archivers: utilities - packers, programs - packers, utility programs that allow you to place copies of files in compressed form in an archive file.

should be distinguished

- archiving program,

- archive format and

Compression methods.

In addition to the actual data compression, modern archivers provide some additional features.

There are several main ones:

- compression of some files and entire directories;

- creation of self-extracting (SFX) archives. That is, to unpack the archive archiving program is not required;

- changing the contents of the archive;

- encryption of archive contents;

- information for restoring an archive in case of partial damage and the possibility

recovery of damaged archives;

- splitting the archive into several parts or volumes;

- console version of the program to work from the command line;

An archiver program is a computer program that allows you to reduce the amount of information and store it without compromising this information. They are used to long-term storage information in a compressed form, creating backups, and transferring files over the network. There are various methods for archiving files, which differ in the degree of file compression, speed of execution, and other parameters.

There are different archivers. Here are some examples of RAR WinRAR (or as it is called "Winrar", Win-RAR) is one of the most convenient and powerful computer archiving programs for the operating system. Windows systems. The name of the program is derived from the words WIN (Windows) and RAR (Roshal ARchive). The author of the program is Evgeny Roshal, by the way, our compatriot. It has a very small size with a rich set of functions and speed. The current version at the time of writing - Winrar Winrar contains a special improved compression algorithm for multimedia files, object libraries and executable programs. Winrar provides the ability to recover damaged archives, encrypt, create multi-volume archives and many other useful and unique features. ZIP Appeared a new version programs for working with ZIP archives. CoffeeCup Free Zip Wizard 2.6 provides an easy way to create a ZIP archive as well as extract and modify existing archives in ZIP format. All actions in the program are carried out using step-by-step Wizards that explain each stage of work, which allows you to quickly understand all the intricacies of archiving files. The program can create self-extracting archives, allows you to adjust the degree of file compression and set a password to open the archive. Using the built-in tools of CoffeeCup Free Zip Wizard 2.6, you can upload it to an FTP server immediately after creating an archive. In addition, there is a function to search for ZIP files on any drives connected to the computer.

7 Z 7-Zip 4.31 archiver that supports many archive formats. 7-Zip has a simple and intuitive interface: you can work in single disk mode, or you can work with archives / files using 2 disk panels at once (similarly file manager). This program should be noted own format creating 7z archives. The compression ratio in it is better than that of the popular ZIP and RAR archive formats, however, the process of archiving files in this format is longer. 7-Zip supports the following archive formats: 7z, ZIP, CAB, RAR, ARJ, GZIP, BZIP2, TAR, CPIO, RPM and DEB. It is possible to create self-extracting archives

Principle of operation The principle of operation of archivers is based on the search for "redundant" information in a file and its subsequent coding in order to reduce the volume. When archiving, the degree of compression of files depends on its format. Archiver programs can reduce the file size to the smallest possible size. The interface of all modern archiver programs is very similar.

File archiving Start the WinRAR 3_0 archiver. Select files (mark a directory), activate the "Add" button on the program toolbar. When creating a new archive, you need to set the archiving parameters: specify the name of the archive file; storage space on disk select the archiving format (rar, zip, exe). choose one of six archiving methods: no compression - places files in an archive without packaging; high-speed - compresses poorly, but quickly; fast; normal - daily backup copy data; good; maximum - the best compression at a lower speed; choose the size of the dictionary. Values ​​64,128, 256, 512 more - better, but slower compression; select the size of splitting into multi-volume archives, usually for storage on floppy disks. Size KB;

It is possible to create a self-extracting file - SFX mode (SelF-tXtracting). no program is needed for unzipping, just run the file for execution, the file is executable and has the .exe extension. on the archive name and parameters panel, set: name of the archive file; archive storage location on disk (default); archive format; compression method; dictionary size (default); volume size; update method; archiving options. to extract files (catalog) you need to select the archive file, activate "Extract" on the program toolbar. By default, the archive is unpacked to the same directory.