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Register (C Programming Language)
In the C programming language, register is a reserved word (or keyword), type modifier, storage class, and hint. The register keyword was deprecated in C++, until it became reserved and unused in C++17. It ''suggests'' that the compiler stores a declared variable in a CPU register (or some other faster location) instead of in random-access memory. If possible depending on the type of CPU and complexity of the program code, it will optimize access to that variable and hence improve the execution time of a program. In C (but not C++ where the keyword is essentially ignored) the location of a variable declared with register cannot be accessed, but the sizeof operator can be applied. Aside from this limitation, register is essentially meaningless in modern compilers due to optimization which will place variables in a register if appropriate regardless of whether the hint is given. For programming of embedded systems register may still be significant; for example the Microchip MPLAB XC32 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Programming Language
''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as co-designed the Unix operating system with which development of the language was closely intertwined. The book was central to the development and popularization of the C programming language and is still widely read and used today. Because the book was co-authored by the original language designer, and because the first edition of the book served for many years as the ''de facto'' standard for the language, the book was regarded by many to be the authoritative reference on C. History C was created by Dennis Ritchie at Bell Labs in the early 1970s as an augmented version of Ken Thompson's B. Another Bell Labs employee, Brian Kernighan, had written the first C tutorial, and he persuaded Ritchie to coauthor a book on the language. Ker ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reserved Word
In a computer language, a reserved word (also known as a reserved identifier) is a word that cannot be used as an identifier, such as the name of a variable, function, or label – it is "reserved from use". This is a syntactic definition, and a reserved word may have no user-defined meaning. A closely related and often conflated notion is a keyword, which is a word with special meaning in a particular context. This is a semantic definition. By contrast, names in a standard library but not built into the language are not considered reserved words or keywords. The terms "reserved word" and "keyword" are often used interchangeably – one may say that a reserved word is "reserved for use as a keyword" – and formal use varies from language to language; for this article we distinguish as above. In general reserved words and keywords need not coincide, but in most modern languages keywords are a subset of reserved words, as this makes parsing easier, since keywords cannot be confused ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Storage Class
Storage may refer to: Goods Containers * Dry cask storage, for storing high-level radioactive waste * Food storage * Intermodal container, cargo shipping * Storage tank Facilities * Garage (residential), a storage space normally used to store cars * Mail storage, storage by mail or delivery service * Self storage, a public storage facility * Warehouse, a commercial building for storage of goods Technology *Cloud storage *Computer data storage, a means to retain digital data *Data storage, general recording and retention of information *Energy storage *Specific storage, of groundwater in an aquifer Arts and entertainment * ''Storage'' (film), a 2009 Australian horror film * ''The Storage'', a 2011 Finnish film * ''Storage'' (album), a 1988 album by Merzbow * ''Storage Wars'', a reality television show * "Storage Wars", an episode of ''One Day at a Time'' (2017 TV series) Other * Storage (memory), a psychological and physiological process See also * * * Container (disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C++17
C++17 is a version of the ISO/IEC 14882 standard for the C++ programming language. C++17 replaced the prior version of the C++ standard, called C++14, and was later replaced by C++20. History Before the C++ Standards Committee fixed a 3-year release cycle, C++17's release date was uncertain. In that time period, the C++17 revision was also called C++1z, following C++0x or C++1x for C++11 and C++1y for C++14. The C++17 specification reached the Draft International Standard (DIS) stage in March 2017. This DIS was unanimously approved, with only editorial comments, and the final standard was published in December 2017. Few changes were made to the C++ Standard Template Library, although some algorithms in the header were given support for explicit parallelization and some syntactic enhancements were made. New features C++17 introduced many new features. The following lists may be incomplete. Language * Making the text message for optional * Allow (as an alternative to ) in a te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compiler
In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program. Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman - Second Edition, 2007 There are many different types of compilers which produce output in different useful forms. A ''cross-compiler'' produces code for a different CPU or operating system than the one on which the cross-compiler itself runs. A ''bootstrap compiler'' is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software include, a program that translates from a low-level language to a h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable (computer Science)
In computer programming, a variable is an abstract storage location paired with an associated symbol, symbolic name, which contains some known or unknown quantity of information referred to as a ''value (computer science), value''; or in simpler terms, a variable is a named container for a particular set of bits or :simple:Data_type, type of data (like Integer (computer science), integer, Floating-point arithmetic, float, String (computer science), string etc...). A variable can eventually be associated with or identified by a memory address. The variable name is the usual way to Reference (computer science), reference the stored value, in addition to referring to the variable itself, depending on the context. This separation of name and content allows the name to be used independently of the exact information it represents. The identifier in computer source code can be Name binding, bound to a Value (computer science), value during Run time (program lifecycle phase), run time, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Processor Register
A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only. In computer architecture, registers are typically addressed by mechanisms other than main memory, but may in some cases be assigned a memory address e.g. DEC PDP-10, ICT 1900. Almost all computers, whether load/store architecture or not, load data from a larger memory into registers where it is used for arithmetic operations and is manipulated or tested by machine instructions. Manipulated data is then often stored back to main memory, either by the same instruction or by a subsequent one. Modern processors use either static or dynamic RAM as main memory, with the latter usually accessed via one or more cache levels. Processor registers are normally at the top of the memory hierarchy, and provide the fastest way to access data. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random-access Memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to be read (computer), read or written in almost the same amount of time irrespective of the physical location of data inside the memory, in contrast with other direct-access data storage media (such as hard disks, CD-RWs, DVD-RWs and the older Magnetic tape data storage, magnetic tapes and drum memory), where the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement. RAM contains multiplexer, multiplexing and demultiplexing circuitry, to connect the data lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, and RAM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sizeof
sizeof is a unary operator in the programming languages C and C++. It generates the storage size of an expression or a data type, measured in the number of ''char''-sized units. Consequently, the construct ''sizeof (char)'' is guaranteed to be ''1''. The actual number of bits of type char is specified by the preprocessor macro , defined in the standard include file limits.h. On most modern computing platforms this is eight bits. The result of ''sizeof'' has an unsigned integer type that is usually denoted by size_t. The operator has a single operand, which is either an expression or the cast of a data type, which is a data type enclosed in parentheses. Data types may not only be primitive types, such as integer and floating-point types, but also pointer types, and compound datatypes ( unions, structs, and C++ classes). Purpose Many programs must know the storage size of a particular datatype. Though for any given implementation of C or C++ the size of a particular datatype i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Counter
In computer science a for-loop or for loop is a control flow statement for specifying iteration. Specifically, a for loop functions by running a section of code repeatedly until a certain condition has been satisfied. For-loops have two parts: a header and a body. The header defines the iteration and the body is the code that is executed once per iteration. The header often declares an explicit loop counter or loop variable. This allows the body to know which iteration is being executed. For-loops are typically used when the number of iterations is known before entering the loop. For-loops can be thought of as shorthands for while-loops which increment and test a loop variable. Various keywords are used to indicate the usage of a for loop: descendants of ALGOL use "for", while descendants of Fortran use "do". There are other possibilities, for example COBOL which uses "PERFORM VARYING". The name ''for-loop'' comes from the word for. For is used as the keyword in many progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optimizing Compiler
In computing, an optimizing compiler is a compiler that tries to minimize or maximize some attributes of an executable computer program. Common requirements are to minimize a program's execution time, memory footprint, storage size, and power consumption (the last three being popular for portable computers). Compiler optimization is generally implemented using a sequence of ''optimizing transformations'', algorithms which take a program and transform it to produce a semantically equivalent output program that uses fewer resources or executes faster. It has been shown that some code optimization problems are NP-complete, or even undecidable. In practice, factors such as the programmer's willingness to wait for the compiler to complete its task place upper limits on the optimizations that a compiler might provide. Optimization is generally a very CPU- and memory-intensive process. In the past, computer memory limitations were also a major factor in limiting which optimizations coul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program Optimization
In computer science, program optimization, code optimization, or software optimization, is the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources. In general, a computer program may be optimized so that it executes more rapidly, or to make it capable of operating with less memory storage or other resources, or draw less power. General Although the word "optimization" shares the same root as "optimal", it is rare for the process of optimization to produce a truly optimal system. A system can generally be made optimal not in absolute terms, but only with respect to a given quality metric, which may be in contrast with other possible metrics. As a result, the optimized system will typically only be optimal in one application or for one audience. One might reduce the amount of time that a program takes to perform some task at the price of making it consume more memory. In an application where memory space is at a premium, on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
