This function performs several tasks, according to the value of the parameter what: LUA. K12 is the number one choice in K-12 online education programs in America. K12 is the trusted provider of online learning for many tuition-free, virtual public schools, as well as homeschooling. Take charge of your child’s. Questo sito utilizza cookie di 'terze parti', ossia cookie installati da un sito diverso tramite il sito che si sta visitando. Chiudendo questo banner, scorrendo questa pagina o cliccando qualunque suo elemento acconsenti all. Diabetes Free Program Review Treatment Diabetes & Alternative Diabetes Treatment FREE STANDARD SHIPPING ON EVERY ORDER. NO OFFER CODE NECESSARY. Upgrade to 2nd Day Shipping for $5.00 or Overnight Shipping for $10.00. Programming language - Wikipedia, the free encyclopedia. A programming language is a formalcomputer language or constructed language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs to control the behavior of a machine or to express algorithms. The earliest known programmable machine preceded the invention of the digital computer and is the automatic flute player described in the 9th century by the brothers Musa in Baghdad, . Many programming languages require computation to be specified in an imperative form (i. Some languages are defined by a specification document (for example, the C programming language is specified by an ISO Standard), while other languages (such as Perl) have a dominant implementation that is treated as a reference. Some languages have both, with the basic language defined by a standard and extensions taken from the dominant implementation being common. Definitions. For example, Post. Script programs are frequently created by another program to control a computer printer or display. More generally, a programming language may describe computation on some, possibly abstract, machine. It is generally accepted that a complete specification for a programming language includes a description, possibly idealized, of a machine or processor for that language. The practical necessity that a programming language support adequate abstractions is expressed by the abstraction principle. All Turing complete languages can implement the same set of algorithms. ANSI/ISO SQL- 9. 2 and Charity are examples of languages that are not Turing complete, yet often called programming languages. XSLT, for example, is a Turing complete XML dialect. One usage describes programming languages as a subset of computer languages. For instance, markup languages are sometimes referred to as computer languages to emphasize that they are not meant to be used for programming. Reynolds emphasizes that formal specification languages are just as much programming languages as are the languages intended for execution. He also argues that textual and even graphical input formats that affect the behavior of a computer are programming languages, despite the fact they are commonly not Turing- complete, and remarks that ignorance of programming language concepts is the reason for many flaws in input formats. The programs, in decimal or binary form, were read in from punched cards or magnetic tape, or toggled in on switches on the front panel of the computer. Absolute machine languages were later termed first- generation programming languages (1. GL). The next step was development of so- called second- generation programming languages (2. GL) or assembly languages, which were still closely tied to the instruction set architecture of the specific computer. These served to make the program much more human- readable, and relieved the programmer of tedious and error- prone address calculations. The first high- level programming languages, or third- generation programming languages (3. GL), were written in the 1. An early high- level programming language to be designed for a computer was Plankalk. However, it was not implemented until 1. However, the program had to be translated into machine code every time it ran, making the process much slower than running the equivalent machine code. At the University of Manchester, Alick Glennie developed Autocode in the early 1. A programming language, it used a compiler to automatically convert the language into machine code. The first code and compiler was developed in 1. Mark 1 computer at the University of Manchester and is considered to be the first compiled high- level programming language. Brooker in 1. 95. Brooker also developed an autocode for the Ferranti Mercury in the 1. University of Manchester. The version for the EDSAC 2 was devised by D. Hartley of University of Cambridge Mathematical Laboratory in 1. Known as EDSAC 2 Autocode, it was a straight development from Mercury Autocode adapted for local circumstances, and was noted for its object code optimisation and source- language diagnostics which were advanced for the time. A contemporary but separate thread of development, Atlas Autocode was developed for the University of Manchester Atlas 1 machine. In 1. 95. 4, language FORTRAN was invented at IBM by John Backus; it was the first widely used high level general purpose programming language to have a functional implementation, as opposed to just a design on paper. It was developed for the UNIVAC I at Remington Rand during the period from 1. Hopper found that business data processing customers were uncomfortable with mathematical notation, and in early 1. English programming language and implemented a prototype. These languages, to varying degrees, provide facilities between assembly languages and high- level languages, and can be used to perform tasks which require direct access to hardware facilities but still provide higher- level control structures and error- checking. The period from the 1. APL introduced array programming and influenced functional programming. These are only a few of the thousands of programming languages and dialects that have been designed in history. The 1. 98. 0s were years of relative consolidation. C++ combined object- oriented and systems programming. The United States government standardized Ada, a systems programming language derived from Pascal and intended for use by defense contractors. In Japan and elsewhere, vast sums were spent investigating so- called . Rather than inventing new paradigms, all of these movements elaborated upon the ideas invented in the previous decades. One important trend in language design for programming large- scale systems during the 1. Modula- 2, Ada, and ML all developed notable module systems in the 1. Perl, originally a Unix scripting tool first released in 1. Java came to be used for server- side programming, and bytecode virtual machines became popular again in commercial settings with their promise of . These developments were not fundamentally novel, rather they were refinements of many existing languages and paradigms (although their syntax was often based on the C family of programming languages). Programming language evolution continues, in both industry and research. Current directions include security and reliability verification, new kinds of modularity (mixins, delegates, aspects), and database integration such as Microsoft's LINQ. Fourth- generation programming languages (4. GL) are a computer programming languages which aim to provide a higher level of abstraction of the internal computer hardware details than 3. GLs. Fifth generation programming languages (5. GL) are programming languages based on solving problems using constraints given to the program, rather than using an algorithm written by a programmer. Elements. These primitives are defined by syntactic and semantic rules which describe their structure and meaning respectively. A programming language's surface form is known as its syntax. Most programming languages are purely textual; they use sequences of text including words, numbers, and punctuation, much like written natural languages. On the other hand, there are some programming languages which are more graphical in nature, using visual relationships between symbols to specify a program. The syntax of a language describes the possible combinations of symbols that form a syntactically correct program. The meaning given to a combination of symbols is handled by semantics (either formal or hard- coded in a reference implementation). Since most languages are textual, this article discusses textual syntax. Programming language syntax is usually defined using a combination of regular expressions (for lexical structure) and Backus. Below is a simple grammar, based on Lisp. Many syntactically correct programs are nonetheless ill- formed, per the language's rules; and may (depending on the language specification and the soundness of the implementation) result in an error on translation or execution. In some cases, such programs may exhibit undefined behavior. Even when a program is well- defined within a language, it may still have a meaning that is not intended by the person who wrote it. Using natural language as an example, it may not be possible to assign a meaning to a grammatically correct sentence or the sentence may be false. But the program would still be syntactically correct, since type declarations provide only semantic information. The grammar needed to specify a programming language can be classified by its position in the Chomsky hierarchy. The syntax of most programming languages can be specified using a Type- 2 grammar, i. Languages that have constructs that allow the programmer to alter the behavior of the parser make syntax analysis an undecidable problem, and generally blur the distinction between parsing and execution. Examples include checking that every identifier is declared before it is used (in languages that require such declarations) or that the labels on the arms of a case statement are distinct. Other forms of static analyses like data flow analysis may also be part of static semantics. Newer programming languages like Java and C# have definite assignment analysis, a form of data flow analysis, as part of their static semantics. Dynamic semantics. For example, the semantics may define the strategy by which expressions are evaluated to values, or the manner in which control structures conditionally execute statements. The dynamic semantics (also known as execution semantics) of a language defines how and when the various constructs of a language should produce a program behavior. There are many ways of defining execution semantics. Natural language is often used to specify the execution semantics of languages commonly used in practice.
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