1 ABSTRACT The Domain “File Compressor” lets you reduce the overall number of bits and bytes in a file so it can be transmitted faster over slower Internet connections, or take up less space on a disk. Domain File Compressor is a System Based Software. The user need not depend on third party software’s like winzip, winrar The main algorithms are: • GZIP algorithm GZip is a software application used for file compression. gzip is short for GNU zip; the program is a free software replacement for the compress program used in early Unix systems, intended for use by the GNU Project.gzip was created by Jean-Loup Gailly and Mark Adler . Version 0.1 was first publicly released on October 31 , 1992 . Version 1.0 followed in February 1993. gzip is based on the DEFLATE algorithm, which is a combination of LZ77 and Huffman coding . “gzip” is often also used to refer to the gzip file format, which is: • a 10-byte header, containing a magic number , a version number and a timestamp • optional extra headers, such as the original file name, • a body, containing a DEFLATE-compressed payload • an 8-byte footer, containing a CRC-32 checksum and the length of the original uncompressed data Although its file format also allows for multiple such streams to be concatenated (zipped files are simply decompressed concatenated as if they were originally one file), gzip is normally used to compress just single files. Compressed archives are typically created by assembling collections of files into a single tar archive, and then compressing that archive with gzip. The final .tar.gz or .tgz file is usually called a tarball . FILE COMPRESSOR
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
ABSTRACT
The Domain “File Compressor” lets you reduce the overall number of bits and bytes in a file so it
can be transmitted faster over slower Internet connections, or take up less space on a disk.
Domain File Compressor is a System Based Software. The user need not depend on third party
software’s like winzip, winrar
The main algorithms are:
• GZIP algorithm
GZip is a software application used for file compression. gzip is short for GNU zip; the program
is a free software replacement for the compress program used in early Unix systems, intended for
use by the GNU Project.gzip was created by Jean-Loup Gailly and Mark Adler. Version 0.1 was
first publicly released on October 31, 1992. Version 1.0 followed in February 1993. gzip is based
on the DEFLATE algorithm, which is a combination of LZ77 and Huffman coding. “gzip” is
often also used to refer to the gzip file format, which is:
• a 10-byte header, containing a magic number, a version number and a timestamp
• optional extra headers, such as the original file name,
• a body, containing a DEFLATE-compressed payload
• an 8-byte footer, containing a CRC-32 checksum and the length of the original
uncompressed data
Although its file format also allows for multiple such streams to be concatenated (zipped files
are simply decompressed concatenated as if they were originally one file), gzip is normally used
to compress just single files. Compressed archives are typically created by assembling
collections of files into a single tar archive, and then compressing that archive with gzip. The
final .tar.gz or .tgz file is usually called a tarball.
Common Language SpecificationCommon Language Specification
Visual Visual BasicBasic
C++
C++
C#C#
J#J#
……
.NET Framework.NET Framework
15
Building Components in the .NET Framework
In the .NET Framework, components are built on a common foundation. You no longer need to
write the code to allow objects to interact directly with each other. In the .NETenvironment, you
no longer need to write component wrappers because components do not use wrappers. The
.NET Framework can interpret the constructs that developers are accustomed to using in object
oriented languages. The .NET Framework fully supports class,inheritance, methods, properties,
events, polymorphism, constructors and other objects oriented constructs.
The Common Language Specification:-
The common Language Specification (CLS) defines the common standards to
which languages and developers must adhere if they want their components and applications to
be widely useable by other .NET compatible languages, The CLS allows Visual Basic .NET
developers to create applications as part of a multiple language team with the knowledge that
there will be no problems integrating the different languages. The CLS even allows Visual
Basic .NET developers to inherit from classes defined in different languages.
Goals of the .NET Framework
The .NET Framework was designed to meet the following goals:
1. Based on Web standards and practices
The .NET Framework fully supports the existing Internet technologies, including
Hypertext Markup Language (HTML), XML, SOAP, Extensible Style sheet
FILE COMPRESSOR
16
Language for Transformations (XSLT), Path, and other Web standards. The .NET
Framework favors loosely connected, stateless Web services.
2. Extensible
The hierarchy of the .NET Framework is not hidden from the developer. You can
access and extend .NET classes (unless they are sealed) by using inheritance. You can
also implement cross-language inheritance.
3. Easy for developers to use
In the .NET Framework, code is organized into hierarchical namespaces and classes.
The framework provides a common type system, referred to as the unified type
system, that is used by and .NET Framework compatible language. In the unified type
system, everything is an object. There are no variant types, there is only one string
type and all string data is Unicode.
4. Designed using unified application models
.NET class functionality is available from any .NET Framework compatible language
or programming model.
FILE COMPRESSOR
17
C# Language
FILE COMPRESSOR
Benefits of the .NET Framework
Based on Web standards and practices
Extensible
Easy for developers to use
Designed using unified application models
Windows APIWindows API
Visual Basic FormsVisual Basic Forms
MFC/ATLMFC/ATL
ASPASP
.NET Framework.NET Framework
18
C# (pronounced C Sharp) is a computer language developed by Microsoft but made available
to the general public through international standards. The current release is termed as 3.0. This series of lessons teach C# (3.0) as a computer language, not to be confused with Microsoft
Visual C# or any other programming environment that uses C#. To follow these lessons, you
should have the ability to create, compile, and execute console applications. You can use the
.NET Framework that includes the csc.exe compiler but, as an alternative, you can (should) use
Microsoft Visual C# 2008 Professional or you can use Microsoft Visual C# 2008 Express Edition
that you can freely download from the Microsoft web site.Features:
• There are no global variables or functions. All methods and members must be declared
within classes. Static members of public classes can substitute for global variables and
functions.
• Local variables cannot shadow variables of the enclosing block, unlike C and C++.
Variable shadowing is often considered confusing by C++ texts.
• C# supports a strict Boolean datatype, bool. Statements that take conditions, such as
while and if, require an expression of a boolean type. While C++ also has a boolean
type, it can be freely converted to and from integers, and expressions such as if(a)
require only that a is convertible to bool, allowing a to be an int, or a pointer. C#
disallows this "integer meaning true or false" approach on the grounds that forcing
programmers to use expressions that return exactly bool can prevent certain types of
programming mistakes such as if (a = b) (use of = instead of ==).
• C# is more typesafe than C++. The only implicit conversions by default are those which
are considered safe, such as widening of integers and conversion from a derived type to a
base type. This is enforced at compile-time, during JIT, and, in some cases, at runtime.
There are no implicit conversions between booleans and integers, nor between
enumeration members and integers (except for literal 0, which can be implicitly
converted to any enumerated type). Any user-defined conversion must be explicitly
marked as explicit or implicit, unlike C++ copy constructors and conversion operators,