Pseudo Code

PseudocodeFrom Wikipedia, the free encyclopedia In computer science and numerical computation, pseudocode is a compact and informal high-level description of the operating principle of a computer program or other algorithm. It uses the structural conventions of a programming language, but is intended for human reading rather than machine reading. Pseudocode typically omits details that are not essential for human understanding of the algorithm, such as variable declarations, system-specific code and some subroutines. The programming language is augmented with natural language descriptions details, where convenient, or with compact mathematical notation. The purpose of using pseudocode is that it is easier for persons to understand than conventional programming language code, and that it is an efficient and environment-independent description of the key principles of an algorithm. It is commonly used in textbooks and scientific publications that are documenting various algorithms, and also in planning of computer program development, for sketching out the structure of the program before the actual coding takes place. No standard for pseudocode syntax exists, as a program in pseudocode is not an executable program. Pseudocode resembles, but should not be confused with, skeleton programs including dummy code, which can be compiled without errors. Flowcharts and UML charts can be thought of as a graphical alternative to pseudocode, but are more spacious on paper. Contents [hide]     1 Application 2 Syntax 3 Mathematical style pseudocode 4 Machine compilation of pseudo-code style languages o o 4.1 Natural language grammar in programming languages 4.2 Mathematical programming languages    5 See also 4.2.1 Alternative forms of pseudocode 6 External links [ edit]Application Textbooks and scientific publications related to computer science and numerical computation often use pseudocode in description of algorithms, so that all programmers can understand them, even if they do not all know the same programming languages. In textbooks, there is usually an accompanying introduction This is an example of pseudocode (for the mathematical game bizz buzz): For i = 1 to 100 set print_number to true if i mod 3 = 0 print "Bizz" and set print_number to false if i mod 5 = 0 print "Buzz" and set print_number to false if print_number. [ edit]Syntax As the name suggests. pseudocode often consists of mathematical notation. C. although any particular writer will generally borrow style and syntax for example control structures from some conventional programming language. [ edit]Mathematical style pseudocode In numerical computation. and ALGOL. For example. pseudocode may therefore vary widely in style. The level of detail of the pseudo-code may in some cases approach that of formalized general-purpose languages. especially an unfamiliar one. from a near-exact imitation of a real programming language at one extreme. C++. as a top-down structuring approach. will often start with a pseudocode description.explaining the particular conventions in use. Popular syntax sources include Pascal. Variable declarations are typically omitted. to a description approaching formatted prose at the other. and is frequently used as a way to describe mathematical algorithms. mixed with the control structures of a conventional programming language. Function calls and blocks of code. the sum operator (capital-sigma notation) or the product operator (capital-pi notation) may represent a for loop and perhaps a selection structure in one expression: . Programmers may also start a project by sketching out the code in pseudocode on paper before writing it in its actual language. pseudocode generally does not actually obey the syntax rules of any particular language. and perhaps also natural language descriptions. is often replaced by a one-line natural language sentence. for example code contained within a loop. Depending on the writer. Lisp. BASIC. Java. there is no systematic standard form. typically from set and matrix theory. and then "translate" that description into the target programming language and modify it to interact correctly with the rest of the program. A programmer who needs to implement a specific algorithm. print i print a newline See also Category: Articles with example pseudocode. This is a compact and often informal notation that can be understood by a wide range of mathematically trained people. and pidgin Ada. These languages are typically dynamically typed. SQL. for example by means of TeX or MathML markup. Such languages may make it easier for a person without knowledge about the language to understand the code and perhaps also to learn the language. AppleScript.Return Normally non-ASCII typesetting is used for the mathematical equations. . resulting in quite talkative code. However. the similarity to natural language is usually more cosmetic than genuine. pidgin Pascal. pidgin Fortran. These are examples of articles that contain mathematical style pseudo code:      Algorithm Conjugate gradient method Ford-Fulkerson algorithm Gauss–Seidel method     Karmarkar's algorithm Particle swarm optimization Stone method Successive over-relaxation Symbolic Cholesky decomposition Tridiagonal matrix algorithm Generalized minimal residual  method  Jacobi eigenvalue algorithm Jacobi method   Mathematical style pseudocode is sometimes referred to as pidgin code. The syntax rules may be just as strict and formal as in conventional programming. parentheses and other special characters are replaced by prepositions. meaning that variable declarations and other boilerplate code can be omitted. for example pidgin ALGOL (the origin of the concept). pidgin C. Lingo. and do not necessarily make development of the programs easier. pidgin BASIC. Inform and to some extent Python. In these languages. [ edit]Machine compilation of pseudo-code style languages language grammar in programming languages [edit]Natural Various attempts to bring elements of natural language grammar into computer programming have produced programming languages such as HyperTalk. or proprietary formula editors. [edit]Mathematical programming languages An alternative to using mathematical pseudocode (involving set theory notation or matrix operations) for documentation of algorithms is to use a formal mathematical programming language that is a mix of non-ASCII mathematical notation and program control structures. Then the code can be parsed and interpreted by a machine. 4GL and 5GL projects are more oriented toward problem solving and systems engineering. . block-structured mode of the third-generation programming languages improved the process of software development. The natural-language. However. In some senses. software engineering arose to handle 3GL development. given the right problem. you could use a language syntax closer to the problem domain. Some array programming languages include vectorized expressions and matrix operations as non-ASCII formulas. the time it takes to develop software. sometimes resulting in inelegant and unmaintainable code. the free encyclopedia A fourth-generation programming language (1970s-1990) (abbreviated 4GL) is a programming language or programming environment designed with a specific purpose in mind. [edit]Alternative forms of pseudocode Since the usual aim of pseudocode is to present a simple form of some algorithm. However. the use of an appropriate 4GL can be spectacularly successful as was seen with MARK-IV and MAPPER (see History Section. The usability improvements obtained by some 4GLs (and their environment) allowed better exploration for heuristic solutions than did the 3GL. and the cost of software development. MathCAD. 3GL development methods can be slow and error-prone. The 4GL was followed by efforts to define and use a5GL. such as the development of commercial business software. Examples are:   A programming language (APL).[citation needed] All 4GLs are designed to reduce programming effort. Examples are:   Z notation Vienna Development Method Specification Language (VDM-SL). the 4GL followed the 3GL in an upward trend toward higher abstraction and statement power. Santa Fe real-time tracking of their freight cars – the productivity gains were estimated to be 8 times over COBOL). mixed with conventional control structures.Several formal specification languages include set theory notation using special characters. They are not always successful in this task. and its dialects APLX and A+. It became clear that some applications could be developed more rapidly by adding a higher-level programming language and methodology which would generate the equivalent of very complicated 3GL instructions with fewer errors.[1] In the history of computer science.[example needed] This would make the expression of ideas in the pseudocode simpler to convey in those domains. Fourth-generation programming language From Wikipedia. With judicious use of a few . measured in function points per staff-month.[2][3] Contents [hide]       1 History 2 Types 3 Some fourth-generation languages 4 See also 5 References 6 External links [edit]History Though used earlier in papers and discussions. each generation (in the sense of the page) is further from the machine (see theComputer Science history in regard to data structure improvements and information hiding). In a sense. 4GL limitations lead to recognition of the need for the 5GL. a 4GL could be business oriented or it could deal with some technical domain. Fourth-generation languages have often been compared to domain-specific programming languages (DSLs). so too did the 4GL open up the development environment to a wider population. A 4GL is defined as a language that supports 12–20 FP/SM. as part of his work on function point analysis. It is this latter nature that is directly associated with 4GL having errors that are harder. This correlates with about 16–27 lines of code per function point implemented in a 4GL.A quantitative definition of 4GL has been set by Capers Jones. In some primitive way. 1979 release). the term 4GL was first used formally by James Martin in his 1982 book Applications Development Without Programmers [4] to refer to non-procedural. to debug. Just as the 3GL offered greater power to the programmer. It can also apply to an approach that looks for greater semantic properties and implementation power. Jones defines the various generations of programming languages in terms of developer productivity. The motivations for the '4GL' inception and continued interest are several. Being further from the machine implies being closer to domain. In terms of applications. Some researchers state that 4GLs are a subset of DSLs.[original research?] The early input scheme for the 4GL supported entry of data within the 72-character limit of the punched card (8 bytes used for sequencing) where a card's tag would identify the type or function. The term can apply to a large set of software products. the 4GL is an example of 'black box' processing. Early 4GL's were included the Informatics MARKIV (1967) product and Sperry's MAPPER (1969 internal use. in many cases. high- level specification languages. Given the wide disparity of concepts and methods across domains. [7] The idea was that it was easier to teach railroad experts to use MAPPER than to teach programmers the "intricacies of railroad operations". a mathematical software company. One example is the MAPPER system developed by Sperry. [edit]Types A number of different types of 4GLs exist: . a whole box or more of cards. greater power ensued. this approach supported highly sophisticated applications. and then just a page or two of Mark IV. Santa Fe railroad used MAPPER to develop a system. The latest variant is embedded in the BIS [6] offering of Unisys. and programming by users.[5] The 72-character metaphor continued for a while as hardware progressed to larger memory and terminal interfaces.[8] One of the early (and portable) languages that had 4GL properties was Ramis developed by Gerald C. rapid prototyping.. from Informatics. Cohen left Mathematica and founded Information Builders to create a similar reporting-oriented 4GL. with the hardware and operating system constraints having a large weight. Though it has roots back to the beginning. When the 4GL was first introduced. An example of this is described on the Nomad page.cards. perhaps." Rawlings offered the following single statement. He reports that James Martin asked Rawlings for a Nomad solution to a standard problem Martin called theEngineer's Problem: "give 6% raises to engineers whose job ratings had an average of 7 or better. Later 4GL types are tied to a database system and are far different from the earlier types in their use of techniques and resources that have resulted from the general improvement of computing with time." Martin provided a "dozen pages of COBOL. Another example of Nomad's power is illustrated by Nicholas Rawlings in his comments for the Computer History Museum about NCSS (see citation below). in a project that was an early example of 4GL. the 4GL deck could offer a wide variety of processing and reporting capability whereas the equivalent functionality coded in a 3GL could subsume. The development of the 4GL was influenced by several factors. MARK-IV is now known as VISION:BUILDER and is offered by Computer Associates. Cohen at Mathematica. called Focus. performing a set-at-a-time operation. the system has proven successful in many applications and has been ported to modern platforms. a disparate mix of hardware and operating systems mandated custom application development support that was specific to the system in order to ensure sales. Even with its limitations.. An interesting twist to the 4GL scene is realization that graphical interfaces and the related reasoning done by the user form a 'language' that is poorly understood. As interfaces improved and allowed longer statement lengths and grammar-driven input handling. the developer uses Tabledriven algorithm programming (See also control tables that can be used for this purpose). case selection and data documentation in the preparation of data for statistical analysis and reporting. See also RPG  Similarly. entity life history diagrams etc. [edit]Some fourth-generation languages General use / versatile     Clarion Clipper Cognos PowerHouse 4GL DataFlex . They usually offer integration with lower level DLLs generated from a typical 3GL for when the need arise for more hardware/OS specific operations.  More recently Oracle Corporation's Oracle Designer and Oracle Developer Suite 4GL products could be integrated to produce database definitions and the forms and reports programs.  Data management 4GLs such as SAS. These types of tools can be used for business application development usually consisting in a package allowing for both business data manipulation and reporting. Instead of using code. file reshaping.  Report-generator programming languages take a description of the data format and the report to generate and from that they either generate the required report directly or they generate a program to generate the report. usually running with a runtime framework and libraries. In other words. A good example of this type of 4GL language is PowerBuilder. instead of coding. therefore they come with GUI screens and report editors. specifications of screens and reports. the developer defines his logic by selecting an operation in a pre-defined list of memory or data table manipulation commands. from which hundreds of thousands of lines of COBOL would be generated overnight. Some 4GLs have integrated tools which allow for the easy specification of all the required information:  James Martin's version of Information Engineering systems development methodology was automated to allow the input of the results of system analysis and design in the form of data flow diagrams. SPSS and Stata provide sophisticated coding commands for data manipulation.  More ambitious 4GLs (sometimes termed fourth generation environments) attempt to automatically generate whole systems from the outputs of CASE tools. entity relationship diagrams. forms generators manage online interactions with the application system users or generate programs to do so. Table-driven (codeless) programming. and possibly also the specification of some additional processing logic.                Discovery Machine Modeler Forté TOOL (transactional object-oriented language) FoxPro IBM Rational EGL (Enterprise Generation Language) Lycia Querix 4GL Omnis Studio SDK Panther PowerBuilder SheerPower4GL (Microsoft Windows Only) SQLWindows/Team Developer Up ! 5GL Uniface (programming language) Visual DataFlex (Microsoft Windows Only) WinDev XBase++ Database query languages         FOCUS Genero Informix-4GL Lycia Querix 4GL NATURAL Progress 4GL Ingres 4GL SQL Report generators        BuildProfessional IDL-PV/WAVE LINC NATURAL Oracle Reports Progress 4GL Query/Results Quest . and reporting languages                              Ab Initio ABAP Aubit-4GL Audit Command Language Clarion Programming Language CorVision Culprit ADS/Online (plus transaction processing) Easytrieve FOCUS GraphTalk IDL IGOR Pro Informix-4GL LANSA LabVIEW MAPPER (Unisys/Sperry) now part of BIS MARK-IV (Sterling/Informatics) now VISION:BUILDER of CA Mathematica NATURAL Nomad PL/SQL Progress 4GL PROIV Lycia Hermes Querix 4GL R Ramis S Scilab .  Report Builder RPG-II Data manipulation. analysis. Mathematical optimization    AIMMS AMPL GAMS Data-stream languages    APE AVS Iris Explorer Database-driven GUI application development      Action Request System Genexus SB+/SystemBuilder Progress Dynamics UNIFACE .       SAS SPSS Stata Synon XBase++ SQR Xquery Backward compatible with SQL and forward compatible with XML data sources. GUI creators         4th Dimension (Software) MATLAB's GUIDE Omnis Studio OpenROAD Progress 4GL AppBuilder Revolution programming language Sculptor 4GL XUL Can be used with Xquery to create web GUI database applications quickly. Hibernate  OutSystems .Screen painters and generators     SB+/SystemBuilder Oracle Forms Progress 4GL ProVision Unify Accell Web development languages   ColdFusion Wavemaker open source. browser-based development platform for Ajax development based on Dojo. Spring.