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Opaque Data Type
In computer science, an opaque data type is a data type whose concrete data structure is not defined in an interface. This enforces information hiding, since its values can only be manipulated by calling subroutines that have access to the missing information. The concrete representation of the type is hidden from its users, and the visible implementation is incomplete. A data type whose representation is visible is called transparent. Opaque data types are frequently used to implement abstract data types. Typical examples of opaque data types include handles for resources provided by an operating system to application software. For example, the POSIX standard for threads defines an application programming interface based on a number of opaque types that represent threads or synchronization primitives like mutexes or condition variables. An opaque pointer is a special case of an opaque data type, a datatype that is declared to be a pointer to a record or data structure of som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical disciplines (including the design and implementation of Computer architecture, hardware and Computer programming, software). Computer science is generally considered an area of research, academic research and distinct from computer programming. 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 for preventing Vulnerability (computing), security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutex
In computer science, a lock or mutex (from mutual exclusion) is a synchronization primitive: a mechanism that enforces limits on access to a resource when there are many threads of execution. A lock is designed to enforce a mutual exclusion concurrency control policy, and with a variety of possible methods there exists multiple unique implementations for different applications. Types Generally, locks are ''advisory locks'', where each thread cooperates by acquiring the lock before accessing the corresponding data. Some systems also implement ''mandatory locks'', where attempting unauthorized access to a locked resource will force an exception in the entity attempting to make the access. The simplest type of lock is a binary semaphore. It provides exclusive access to the locked data. Other schemes also provide shared access for reading data. Other widely implemented access modes are exclusive, intend-to-exclude and intend-to-upgrade. Another way to classify locks is by what happ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Address
In computing, a memory address is a reference to a specific memory location used at various levels by software and hardware. Memory addresses are fixed-length sequences of digits conventionally displayed and manipulated as unsigned integers. Such numerical semantic bases itself upon features of CPU (such as the instruction pointer and incremental address registers), as well upon use of the memory like an array endorsed by various programming languages. Types Physical addresses A digital computer's main memory consists of many memory locations. Each memory location has a physical address which is a code. The CPU (or other device) can use the code to access the corresponding memory location. Generally only system software, i.e. the BIOS, operating systems, and some specialized utility programs (e.g., memory testers), address physical memory using machine code operands or processor registers, instructing the CPU to direct a hardware device, called the memory controller, to use the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Record (computer Science)
In computer science, a record (also called a structure, struct, or compound data) is a basic data structure. Records in a database or spreadsheet are usually called "rows". A record is a collection of ''fields'', possibly of different data types, typically in a fixed number and sequence. The fields of a record may also be called ''members'', particularly in object-oriented programming; fields may also be called ''elements'', though this risks confusion with the elements of a collection. For example, a date could be stored as a record containing a numeric year field, a month field represented as a string, and a numeric day-of-month field. A personnel record might contain a name, a salary, and a rank. A Circle record might contain a center and a radius—in this instance, the center itself might be represented as a point record containing x and y coordinates. Records are distinguished from arrays by the fact that their number of fields is determined in the definition of the rec ... [...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] |
The 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] |
C File Input/output
The C programming language provides many standard library functions for file input and output. These functions make up the bulk of the C standard library header . The functionality descends from a "portable I/O package" written by Mike Lesk at Bell Labs in the early 1970s, and officially became part of the Unix operating system in Version 7. The I/O functionality of C is fairly low-level by modern standards; C abstracts all file operations into operations on streams of bytes, which may be "input streams" or "output streams". Unlike some earlier programming languages, C has no direct support for random-access data files; to read from a record in the middle of a file, the programmer must create a stream, seek to the middle of the file, and then read bytes in sequence from the stream. The stream model of file I/O was popularized by Unix, which was developed concurrently with the C programming language itself. The vast majority of modern operating systems have inherited stream ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Input And Output
In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals or data received by the system and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation. are the pieces of hardware used by a human (or other system) to communicate with a computer. For instance, a keyboard or computer mouse is an input device for a computer, while monitors and printers are output devices. Devices for communication between computers, such as modems and network cards, typically perform both input and output operations. Any interaction with the system by a interactor is an input and the reaction the system responds is called the output. The designation of a device as either input or output depends on perspective. Mice an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer File
A computer file is a computer resource for recording data in a computer storage device, primarily identified by its file name. Just as words can be written to paper, so can data be written to a computer file. Files can be shared with and transferred between computers and mobile devices via removable media, networks, or the Internet. Different types of computer files are designed for different purposes. A file may be designed to store an Image, a written message, a video, a computer program, or any wide variety of other kinds of data. Certain files can store multiple data types at once. By using computer programs, a person can open, read, change, save, and close a computer file. Computer files may be reopened, modified, and copied an arbitrary number of times. Files are typically organized in a file system, which tracks file locations on the disk and enables user access. Etymology The word "file" derives from the Latin ''filum'' ("a thread"). "File" was used in the conte ... [...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] |
Standard Library
In computer programming, a standard library is the library made available across implementations of a programming language. These libraries are conventionally described in programming language specifications; however, contents of a language's associated library may also be determined (in part or whole) by more informal practices of a language's community. Overview A language's standard library is often treated as part of the language by its users, although the designers may have treated it as a separate entity. Many language specifications define a core set that must be made available in all implementations, in addition to other portions which may be optionally implemented. The line between a language and its libraries therefore differs from language to language. Indeed, some languages are designed so that the meanings of certain syntactic constructs cannot even be described without referring to the core library. For example, in Java, a string literal is defined as an instance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Record (computer Science)
In computer science, a record (also called a structure, struct, or compound data) is a basic data structure. Records in a database or spreadsheet are usually called "rows". A record is a collection of ''fields'', possibly of different data types, typically in a fixed number and sequence. The fields of a record may also be called ''members'', particularly in object-oriented programming; fields may also be called ''elements'', though this risks confusion with the elements of a collection. For example, a date could be stored as a record containing a numeric year field, a month field represented as a string, and a numeric day-of-month field. A personnel record might contain a name, a salary, and a rank. A Circle record might contain a center and a radius—in this instance, the center itself might be represented as a point record containing x and y coordinates. Records are distinguished from arrays by the fact that their number of fields is determined in the definition of the rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
