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Expression (computer Science)
In computer science, an expression is a Syntax (programming languages), syntactic entity in a programming language that may be evaluated to determine its value (computer science), value. It is a combination of one or more Constant (programming), constants, variable (programming), variables, function (programming), functions, and operator (programming), operators that the programming language interprets (according to its particular Order of operations, rules of precedence and of Associative property, association) and computes to produce ("to return", in a state (computer science), stateful environment) another value. This process, for mathematical expressions, is called ''evaluation''. In simple settings, the return type, resulting value is usually one of various primitive data type, primitive types, such as string (computer science), string, boolean expression, boolean, or numerical (such as integer (computer science), integer, floating-point number, floating-point, or complex data t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Integer (computer Science)
In computer science, an integer is a datum of integral data type, a data type that represents some interval (mathematics), range of mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values. Integers are commonly represented in a computer as a group of binary digits (bits). The size of the grouping varies so the set of integer sizes available varies between different types of computers. Computer hardware nearly always provides a way to represent a processor word size, register or memory address as an integer. Value and representation The ''value'' of an item with an integral type is the mathematical integer that it corresponds to. Integral types may be ''unsigned'' (capable of representing only non-negative integers) or ''signed'' (capable of representing negative integers as well). An integer value is typically specified in the source code of a program as a sequence of digits optionally prefixed with + or −. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Cache Memory
In computing, a cache ( ) is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests that can be served from the cache, the faster the system performs. To be cost-effective, caches must be relatively small. Nevertheless, caches are effective in many areas of computing because typical computer applications access data with a high degree of locality of reference. Such access patterns exhibit temporal locality, where data is requested that has been recently requested, and spatial locality, where data is requested that is stored near data that has already be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Statement (programming)
In computer programming, a statement is a syntactic unit of an imperative programming language that expresses some action to be carried out. A program written in such a language is formed by a sequence of one or more statements. A statement may have internal components (e.g. expressions). Many programming languages (e.g. Ada, Algol 60, C, Java, Pascal) make a distinction between statements and definitions/declarations. A definition or declaration specifies the data on which a program is to operate, while a statement specifies the actions to be taken with that data. Statements which cannot contain other statements are ''simple''; those which can contain other statements are ''compound''. The appearance of a statement (and indeed a program) is determined by its syntax or grammar. The meaning of a statement is determined by its semantics. Simple statements Simple statements are complete in themselves; these include assignments, subroutine calls, and a few statements which may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Referential Transparency
In analytic philosophy and computer science, referential transparency and referential opacity are properties of linguistic constructions, and by extension of languages. A linguistic construction is called ''referentially transparent'' when for any expression built from it, Rewriting, replacing a subexpression with another one that Denotation, denotes the same value does not change the value of the expression. Also: Otherwise, it is called ''referentially opaque''. Each expression built from a referentially opaque linguistic construction states something about a subexpression, whereas each expression built from a referentially transparent linguistic construction states something not about a subexpression, meaning that the subexpressions are ‘transparent’ to the expression, acting merely as ‘references’ to something else. For example, the linguistic construction ‘_ was wise’ is referentially transparent (e.g., ''Socrates was wise'' is equivalent to ''The founder of Weste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Side Effect (computer Science)
In computer science, an operation, function or expression is said to have a side effect if it has any observable effect other than its primary effect of reading the value of its arguments and returning a value to the invoker of the operation. Example side effects include modifying a non-local variable, a static local variable or a mutable argument passed by reference; raising errors or exceptions; performing I/O; or calling other functions with side-effects. In the presence of side effects, a program's behaviour may depend on history; that is, the order of evaluation matters. Understanding and debugging a function with side effects requires knowledge about the context and its possible histories. Side effects play an important role in the design and analysis of programming languages. The degree to which side effects are used depends on the programming paradigm. For example, imperative programming is commonly used to produce side effects, to update a system's state. By contrast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Void Type
The void type, in several programming languages, more so curly bracket programming languages derived from C and ALGOL 68, is the return type of a function that returns normally, but provides no result value to its caller. Usually such functions are called for their side effects, such as performing some task or writing to their output parameters. The use of the void data type in such context is comparable to ''procedures'' in Pascal and syntactic constructs which define ''subroutines'' in Visual Basic. It is also similar to the unit type used in functional programming languages and type theory. See Unit type#In programming languages for a comparison. C and C++ also support the pointer to void type (specified as void *), but this is an unrelated notion. Variables of this type are pointers to data of an ''unspecified'' type, so in this context (but not the others) void * acts roughly like a universal or top type. A program can convert a pointer to any type of data (except a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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C (programming Language)
C (''pronounced'' '' – like the letter c'') is a general-purpose 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 Central processing unit, CPUs. It has found lasting use in operating systems code (especially in Kernel (operating system), kernels), device drivers, and protocol stacks, but its use in application software has been decreasing. 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 most widely used programming langu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Relational Operator
In computer science, a relational operator is a programming language construct or operator that tests or defines some kind of relation between two entities. These include numerical equality (e.g., ) and inequalities (e.g., ). In programming languages that include a distinct boolean data type in their type system, like Pascal, Ada, Python or Java, these operators usually evaluate to true or false, depending on if the conditional relationship between the two operands holds or not. In languages such as C, relational operators return the integers 0 or 1, where 0 stands for false and any non-zero value stands for true. An expression created using a relational operator forms what is termed a ''relational expression'' or a ''condition''. Relational operators can be seen as special cases of logical predicates. Equality Usage Equality is used in many programming language constructs and data types. It is used to test if an element already exists in a set, or to access to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Memory (computer)
Computer memory stores information, such as data and programs, for immediate use in the computer. The term ''memory'' is often synonymous with the terms '' RAM,'' ''main memory,'' or ''primary storage.'' Archaic synonyms for main memory include ''core'' (for magnetic core memory) and ''store''. Main memory operates at a high speed compared to mass storage which is slower but less expensive per bit and higher in capacity. Besides storing opened programs and data being actively processed, computer memory serves as a mass storage cache and write buffer to improve both reading and writing performance. Operating systems borrow RAM capacity for caching so long as it is not needed by running software. If needed, contents of the computer memory can be transferred to storage; a common way of doing this is through a memory management technique called ''virtual memory''. Modern computer memory is implemented as semiconductor memory, where data is stored within memory cells built from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Arithmetic Expression
In mathematics, an expression is a written arrangement of symbols following the context-dependent, syntactic conventions of mathematical notation. Symbols can denote numbers, variables, operations, and functions. Other symbols include punctuation marks and brackets, used for grouping where there is not a well-defined order of operations. Expressions are commonly distinguished from ''formulas'': expressions are a kind of mathematical object, whereas formulas are statements ''about'' mathematical objects. This is analogous to natural language, where a noun phrase refers to an object, and a whole sentence refers to a fact. For example, 8x-5 is an expression, while the inequality 8x-5 \geq 3 is a formula. To ''evaluate'' an expression means to find a numerical value equivalent to the expression. Expressions can be ''evaluated'' or ''simplified'' by replacing operations that appear in them with their result. For example, the expression 8\times 2-5 simplifies to 16-5, and ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Syntactic
In linguistics, syntax ( ) is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure (constituency), agreement, the nature of crosslinguistic variation, and the relationship between form and meaning (semantics). Diverse approaches, such as generative grammar and functional grammar, offer unique perspectives on syntax, reflecting its complexity and centrality to understanding human language. Etymology The word ''syntax'' comes from the ancient Greek word , meaning an orderly or systematic arrangement, which consists of (''syn-'', "together" or "alike"), and (''táxis'', "arrangement"). In Hellenistic Greek, this also specifically developed a use referring to the grammatical order of words, with a slightly altered spelling: . The English term, which first appeared in 1548, is partly borrowed from Latin () and Greek, though the Lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |