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PCASTL
The PCASTL (an acronym for ''by Parent and Childset Accessible Syntax Tree Language'') is an interpreted high-level programming language. It was created in 2008 by Philippe Choquette. The PCASTL is designed to ease the writing of self-modifying code. The language has reserved words parent and childset to access the nodes of the syntax tree of the currently written code. Hello world The "Hello world program" is quite simple: "Hello, world!" or print("Hello, world!") will do the same. Syntax The syntax of PCASTL is derived from programming languages C and R. The source of R version 2.5.1 has been studied to write the grammar and the lexer used in the PCASTL interpreter. Influences Like in R, statements can, but do not have to, be separated by semicolons. Like in R, a variable can change type in a session. Like in C and R, PCASTL uses balanced brackets () to make blocks. Operators found in PCASTL have the same precedence and associativity as their counterparts in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-modifying Code
In computer science, self-modifying code (SMC) is code that alters its own instructions while it is executing – usually to reduce the instruction path length and improve performance or simply to reduce otherwise repetitively similar code, thus simplifying maintenance. The term is usually only applied to code where the self-modification is intentional, not in situations where code accidentally modifies itself due to an error such as a buffer overflow. Self-modifying code can involve overwriting existing instructions or generating new code at run time and transferring control to that code. Self-modification can be used as an alternative to the method of "flag setting" and conditional program branching, used primarily to reduce the number of times a condition needs to be tested. The method is frequently used for conditionally invoking test/debugging code without requiring additional computational overhead for every input/output cycle. The modifications may be performed: * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-modifying Code
In computer science, self-modifying code (SMC) is code that alters its own instructions while it is executing – usually to reduce the instruction path length and improve performance or simply to reduce otherwise repetitively similar code, thus simplifying maintenance. The term is usually only applied to code where the self-modification is intentional, not in situations where code accidentally modifies itself due to an error such as a buffer overflow. Self-modifying code can involve overwriting existing instructions or generating new code at run time and transferring control to that code. Self-modification can be used as an alternative to the method of "flag setting" and conditional program branching, used primarily to reduce the number of times a condition needs to be tested. The method is frequently used for conditionally invoking test/debugging code without requiring additional computational overhead for every input/output cycle. The modifications may be performed: * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C (programming Language)
C (''pronounced like the letter c'') is a General-purpose language, general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems, device drivers, protocol stacks, though decreasingly for application software. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the measuring programming language popularity, most widely used programming languages, with C compilers avail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Session (computer Science)
In computer science and networking in particular, a session is a time-delimited two-way link, a practical (relatively high) layer in the tcp/ip protocol enabling interactive expression and information exchange between two or more communication devices or ends – be they computers, automated systems, or live active users (see login session). A session is established at a certain point in time, and then ‘torn down’ - brought to an end - at some later point. An established communication session may involve more than one message in each direction. A session is typically stateful, meaning that at least one of the communicating parties needs to hold current state information and save information about the session history to be able to communicate, as opposed to stateless communication, where the communication consists of independent requests with responses. An established session is the basic requirement to perform a connection-oriented communication. A session also is the basic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Procedural Programming Languages
Procedural programming is a programming paradigm, derived from imperative programming, based on the concept of the ''procedure call''. Procedures (a type of routine or subroutine) simply contain a series of computational steps to be carried out. Any given procedure might be called at any point during a program's execution, including by other procedures or itself. The first major procedural programming languages appeared circa 1957–1964, including Fortran, ALGOL, COBOL, PL/I and BASIC. Pascal and C were published circa 1970–1972. Computer processors provide hardware support for procedural programming through a stack register and instructions for calling procedures and returning from them. Hardware support for other types of programming is possible, but no attempt was commercially successful (for example Lisp machines or Java processors). Procedures and modularity Modularity is generally desirable, especially in large, complicated programs. Inputs are usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Compilers And Interpreters
Free may refer to: Concept * Freedom, having the ability to do something, without having to obey anyone/anything * Freethought, a position that beliefs should be formed only on the basis of logic, reason, and empiricism * Emancipate, to procure political rights, as for a disenfranchised group * Free will, control exercised by rational agents over their actions and decisions * Free of charge, also known as gratis. See Gratis vs libre. Computing * Free (programming), a function that releases dynamically allocated memory for reuse * Free format, a file format which can be used without restrictions * Free software, software usable and distributable with few restrictions and no payment * Freeware, a broader class of software available at no cost Mathematics * Free object ** Free abelian group ** Free algebra ** Free group ** Free module ** Free semigroup * Free variable People * Free (surname) * Free (rapper) (born 1968), or Free Marie, American rapper and media personal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reference (computer Science)
In computer programming, a reference is a value that enables a program to indirectly access a particular data, such as a variable's value or a record, in the computer's memory or in some other storage device. The reference is said to refer to the datum, and accessing the datum is called dereferencing the reference. A reference is distinct from the datum itself. A reference is an abstract data type and may be implemented in many ways. Typically, a reference refers to data stored in memory on a given system, and its internal value is the memory address of the data, i.e. a reference is implemented as a pointer. For this reason a reference is often said to "point to" the data. Other implementations include an offset (difference) between the datum's address and some fixed "base" address, an index, unique key, or identifier used in a lookup operation into an array or table, an operating system handle, a physical address on a storage device, or a network address such as a URL. For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comment (computing)
In computer programming, a comment is a programmer-readable explanation or ''annotation'' in the source code of a computer program. They are added with the purpose of making the source code easier for humans to understand, and are generally ignored by compilers and interpreters.Source code can be divided into ''program code'' (which consists of machine-translatable instructions); and ''comments'' (which include human-readable notes and other kinds of annotations in support of the program code). The syntax of comments in various programming languages varies considerably. Comments are sometimes also processed in various ways to generate documentation external to the source code itself by documentation generators, or used for integration with source code management systems and other kinds of external programming tools. The flexibility provided by comments allows for a wide degree of variability, but formal conventions for their use are commonly part of programming style guides. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subroutine
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Functions may be defined within programs, or separately in libraries that can be used by many programs. In different programming languages, a function may be called a routine, subprogram, subroutine, method, or procedure. Technically, these terms all have different definitions, and the nomenclature varies from language to language. The generic umbrella term ''callable unit'' is sometimes used. A function is often coded so that it can be started several times and from several places during one execution of the program, including from other functions, and then branch back (''return'') to the next instruction after the ''call'', once the function's task is done. The idea of a subroutine was initially conceived by John Mauchly during his work on ENIAC, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Addison-Wesley
Addison-Wesley is an American publisher of textbooks and computer literature. It is an imprint of Pearson PLC, a global publishing and education company. In addition to publishing books, Addison-Wesley also distributes its technical titles through the O'Reilly Online Learning e-reference service. Addison-Wesley's majority of sales derive from the United States (55%) and Europe (22%). The Addison-Wesley Professional Imprint produces content including books, eBooks, and video for the professional IT worker including developers, programmers, managers, system administrators. Classic titles include ''The Art of Computer Programming'', ''The C++ Programming Language'', ''The Mythical Man-Month'', and ''Design Patterns''. History Lew Addison Cummings and Melbourne Wesley Cummings founded Addison-Wesley in 1942, with the first book published by Addison-Wesley being Massachusetts Institute of Technology professor Francis Weston Sears' ''Mechanics''. Its first computer book was ''Progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operator Associativity
In programming language theory, the associativity of an operator is a property that determines how operators of the same precedence are grouped in the absence of parentheses. If an operand is both preceded and followed by operators (for example, ^ 3 ^), and those operators have equal precedence, then the operand may be used as input to two different operations (i.e. the two operations indicated by the two operators). The choice of which operations to apply the operand to, is determined by the associativity of the operators. Operators may be associative (meaning the operations can be grouped arbitrarily), left-associative (meaning the operations are grouped from the left), right-associative (meaning the operations are grouped from the right) or non-associative (meaning operations cannot be chained, often because the output type is incompatible with the input types). The associativity and precedence of an operator is a part of the definition of the programming language; different p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order Of Operations
In mathematics and computer programming, the order of operations (or operator precedence) is a collection of rules that reflect conventions about which procedures to perform first in order to evaluate a given mathematical expression. For example, in mathematics and most computer languages, multiplication is granted a higher precedence than addition, and it has been this way since the introduction of modern algebraic notation. Thus, the expression is interpreted to have the value , and not . When exponents were introduced in the 16th and 17th centuries, they were given precedence over both addition and multiplication, and could be placed only as a superscript to the right of their base. Thus and . These conventions exist to eliminate notational ambiguity, while allowing notation to be as brief as possible. Where it is desired to override the precedence conventions, or even simply to emphasize them, parentheses ( ) can be used. For example, forces addition to precede multipli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
