Source code
{{dablink|Not to be confused with
source coding.}}
thumb|right|300px|An illustration of Java source code with prologue comments indicated in red and inline comments indicated in green. Program code is indicated in blue.In
computer science,
source code (commonly just
source or
code) is any sequence of statements or declarations written in some
human-readable computer
programming language.
Source code is written in a programming language, which is usually a simplified form of the English language to reduce ambiguity.
Source code allows the programmer to communicate with the computer using a reserved number of instructions.The source code which constitutes a
program is usually held in one or more
text files, sometimes stored in databases as
stored procedures and may also appear as
code snippets printed in books or other media. A large collection of source code files may be organized into a
directory tree, in which case it may also be known as a
source tree.
A computer program's
source code is the collection of files needed to convert from human-readable form to some kind of computer-executable form. The source code may be converted into an
executable file by a
compiler, or executed
on the fly from the human readable form with the aid of an
interpreter.The
code base of a
programming project is the larger collection of all the source code of all the
computer programs which make up the project.
Purposes
Source code is primarily used as input to the process that produces an executable program (ie., it is
compiled or
interpreted). It is also used as a method of communicating
algorithms between people (eg.,
code snippets in books).{{Fact|date=May 2008}}
Programmers often find it helpful to review existing source code to learn about programming techniques.{{Fact|date=May 2008}} The sharing of source code between developers is frequently cited as a contributing factor to the maturation of their programming skills.{{Fact|date=May 2008}} Some people consider source code an expressive
artistic medium.
(1)Porting software to other
computer platforms is usually prohibitively difficult without source code. Without the source code for a particular piece of software, portability is generally very expensive.
Binary translation can sometimes be used to run a program when only the executable form rather than the source code is available.
Decompilation can be used to generate source code, either in
assembly code or in a
high level language.Programmers frequently adapt source code from one piece of software to use in other projects, a concept known as
software reusability.
Organization
The source code for a particular piece of software may be contained in a single file or many files. Though uncommon, a program's source code is not necessarily all written in the same programming language.{{Fact|date=May 2008}} For example, a program written primarily in the
C programming language, might have portions written in
Assembly language for optimization purposes. It is also possible for some components of a piece of software to be written and compiled separately, in an arbitrary programming language, and later integrated into the software using a technique called
library linking. This is the case in some languages, such as
Java: each class is compiled separately into a file and linked by the interpreter at runtime. Yet another method is to make the main program an interpreter for a programming language{{Fact|date=May 2008}}, either designed specifically for the application in question or general-purpose, and then write the bulk of the actual user functionality as
macros or other forms of add-ins in this language, an approach taken for example by the
GNU Emacs text editor.Moderately complex software customarily requires the compilation or assembly of several, sometimes dozens or even hundreds, of different source code files. In these cases, instructions for compilations, such as a
Makefile, are included with the source code. These describe the relationships among the source code files, and contain information about how they are to be compiled. The
revision control system is another tool frequently used by developers for source code maintenance.
Licensing
Software, and its accompanying source code, typically falls within one of two licensing paradigms:
free software and
proprietary software. Generally speaking, software is
free if the source code is free to use, distribute, modify and study, and
proprietary if the source code is kept secret, or is privately owned and restricted. The provisions of the various copyright laws are often used for this purpose, though
trade secrecy and
patents are also relied upon. Additionally,
retail software usually comes with an
end-user license agreement (EULA) which typically prohibits
decompilation,
reverse engineering, analysis, modification, or circumventing a
copy protection. Types of source code protection -- beyond traditional
compilation to
object code -- include code encryption,
code obfuscation or
code morphing.
Legal issues in the United States
{{update}}As of 2003, court systems are in the process of deciding whether source code should be considered a Constitutionally protected form of
free speech in the United States. Proponents of the free speech argument claim that because source code conveys information to programmers, is written in a language, and can be used to share humour and other artistic pursuits, it is a protected form of communication. The opposing view is that source code is functional, more than artistic speech, and is thus not protected by
First Amendment Rights of the
U.S. Constitution.One of the first court cases regarding the nature of source code as free speech involved
University of California mathematics professor
Dan Bernstein, who had published on the internet the source code for an
encryption program that he created. At the time, encryption algorithms were classified as
munitions by the United States government; exporting encryption to other countries was considered an issue of
national security, and had to be approved by the
State Department. The
Electronic Frontier Foundation sued the
U.S. government on Bernstein's behalf; the court ruled that source code was free speech, protected by the First Amendment.In 2000, in a related court case, the issue was again brought under some scrutiny when the
Motion Picture Association of America (MPAA) sued the 'hacker' magazine
2600 and a number of other websites for distributing the source code to
DeCSS, an algorithm capable of decrypting scrambled
DVD discs. The algorithm was developed to allow people to play legally purchased DVDs on the
Linux operating system, which had no DVD software at the time. The US
District court decision favored the MPAA;
2600 magazine was prohibited from posting or linking to the source code on their website. This ruling was widely considered a victory for the supporters of the
Digital Millennium Copyright Act, as it established a
legal precedent for the notion that source code is not Constitutionally protected free speech. It was affirmed by the
Appeals Court and
as of late 2003 is being appealed to the
US Supreme Court.
Quality
The way a program is written can have important consequences for its maintainers. Many source code
programming style guides, which stress readability and some language-specific conventions are aimed at the maintenance of the software source code, which involves debugging and updating. Other priorities, such as the speed of the programs execution, or the ability to compile the program for multiple architectures, often make code readability a less important consideration, since code
quality depends entirely on its
purpose.
See also
{{Wiktionarypar|source code}}
References
-
["Art and Computer Programming" ONLamp.com, (2005)]
(VEW04) "Using a Decompiler for Real-World Source Recovery", M Van Emmerik and T Waddington, the
Working Conference on Reverse Engineering, Delft, Netherlands, 9th-12th November 2004.
Extended version of the paper.
External links
Bronkodeكود مصدريКрынічны кодIzvorni kodCodi fontZdrojový kódKildekodeQuelltextLähtekoodΠηγαίος κώδικαςCódigo fuenteFontkodoIturburu kodeCode sourceCódigo fonte소스 코드Izvorni kodKode sumberCodice sorgenteקוד מקורPirmkodsIšeitinis kodasForráskódKod sumberBroncodeソースコードKildekodeKod źródłowyCódigo fonteИсходный кодSource codeZdrojový kódIzvorna kodaLähdekoodiKällkodซอร์สโค้ดMã nguồnKaynak koduПрограмний код源代码
(...as imported from WP)
article has not been saved locally
