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Information about Code (computer Programming)

Not to be confused with source coding.
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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 and/or declarations written in some human-readable computer programming language.

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 sometimes used as a method of communicating algorithms between people (eg., code snippets in books).

Programmers often find it helpful to review existing source code to learn about programming techniques. The sharing of source code between developers is frequently cited as a contributing factor to the maturation of their programming skills. Source code can be an expressive artistic medium; consider, for example, obfuscated code or PerlMonks.Org.

Source code is a vital component in the activity of porting software to alternative computer platforms. 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 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. A program's source code is not necessarily all written in the same programming language; for example, it is common for a program to be written primarily in the C programming language, with some 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. In some languages, such as Java, this is essentially how each file is handled; each is compiled separately and linked at runtime. Yet another method is to make the main program an interpreter for a programming language, 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. This complexity is reduced considerably by the inclusion of a Makefile with the source code, which describes the relationships among the source code files, and contains information about how they are to be compiled. The revision control system is another tool frequently used by developers for source code maintenance.

Licensing

Main article: software license
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, source code of retail software has licensing that prevents 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

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

Main article: Software 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 issues also come into considering whether code is well written, such as the logical structuring of the code into manageable sections.

References

(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.

See also

External Links

data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an un-encoded representation would use through use of specific encoding schemes.
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Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems.
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Human-readable refers to a representation of information that can be naturally read by humans. In most contexts, the alternative representation is data primarily designed for reading by computers.
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A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. Programming languages, like natural languagess, are defined by syntactic and semantic rules which describe their structure and meaning respectively.
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Program may refer to:
  • An architectural brief
  • Computer program
  • Radio programming, or a radio program
  • Television program
  • Webcast
  • Program (management)
  • 12-step program
  • Program (The Animatrix), a short film in The Animatrix series

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text file.]]

A text file is a generic description of a kind of computer file in a computer file system.[1] At this generic level of description, there are two kinds of computer files: 1) text files; and 2) binary files.
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A stored procedure is a subroutine available to applications accessing a relational database system. Stored procedures (sometimes called a sproc or SP) are actually stored in the database.
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Snippet is a programming term for a small region of re-usable source code or text. Ordinarily, these are formally-defined operative units to incorporate into larger programming modules.
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In computing, a directory, catalog, or folder[1] is an entity in a file system which contains a group of files and/or other directories. A typical file system may contain thousands (or even hundreds of thousands) of directories.
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A computer program is one or more instructions that are intended for execution by a computer. Specifically, it is a symbol or combination of symbols forming an algorithm that may or may not terminate, and that algorithm is written in a programming language.
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executable or executable file, in computer science, is a file whose contents are meant to be interpreted as a program by a computer.

While a file in source form may be executable, such a file is usually referred to as a "script.
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compiler is a computer program (or set of programs) that translates text written in a computer language (the source language) into another computer language (the target language).
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Colloquial use

In colloquial use, on the fly means in a hurry, generally involving haste or carelessness. Something created when needed.

Ice hockey

In ice hockey, particularly in organized leagues where the teams have substitutable players (examples include the
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In computer science, an interpreter is a computer program that executes, or performs, instructions written in a computer programming language. Interpretation is one of the two major ways in which a programming language can be implemented, the other being compilation.
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Computer programming (often shortened to programming or coding) is the process of writing, testing, and maintaining the source code of computer programs. The source code is written in a programming language.
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A computer program is one or more instructions that are intended for execution by a computer. Specifically, it is a symbol or combination of symbols forming an algorithm that may or may not terminate, and that algorithm is written in a programming language.
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compiler is a computer program (or set of programs) that translates text written in a computer language (the source language) into another computer language (the target language).
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Interpreter can mean one of the following:
  • Interpreter (communication), a person who facilitates dialogue between parties who use different languages.
  • Interpreter (computing), a program designed to run other non-executable programs directly.

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In mathematics, computing, linguistics, and related disciplines, an algorithm is a finite list of well-defined instructions for accomplishing some task that, given an initial state, will proceed through a well-defined series of successive states, eventually terminating in an
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Snippet is a programming term for a small region of re-usable source code or text. Ordinarily, these are formally-defined operative units to incorporate into larger programming modules.
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programmer or software developer is someone who programs computers, that is, one who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software.
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For other meanings of the word, see .
In the arts, media (plural of medium) are the materials and techniques used by an artist to produce a work.
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Obfuscated code is source code that is (usually intentionally) very hard to read and understand. Some languages are more prone to obfuscation than others. C, C++ and Perl are most often cited as easily obfuscatable languages.
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porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed (e.g. different CPU, operating system, or third party library).
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In computing, binary translation is the emulation of one instruction set by another through translation of code. Sequences of instructions are translated from the source to the target instruction set.
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A decompiler is the name given to a computer program that performs the reverse operation to that of a compiler. That is, it translates a file containing information at a relatively low level of abstraction (usually designed to be computer readable rather than human readable) in to
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Assembly may refer to:

Politics

  • Deliberative assembly
  • General Assembly
  • House of Assembly

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A high-level programming language is a programming language that, in comparison to low-level programming languages, may be more abstract, easier to use, or more portable across platforms.
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In computer science and software engineering, reusability is the likelihood a segment of source code can be used again to add new functionalities with slight or no modification.
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C

The C Programming Language, Brian Kernighan and Dennis Ritchie, the original edition that served for many years as an informal specification of the language.
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