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Iostream
In the C++ programming language, input/output library refers to a family of class templates and supporting functions in the C++ Standard Library that implement stream-based input/output capabilities. It is an object-oriented alternative to C's FILE-based streams from the C standard library. History Bjarne Stroustrup, the creator of C++, wrote the first version of the stream I/O library in 1984, as a type-safe and extensible alternative to C's I/O library. The library has undergone a number of enhancements since this early version, including the introduction of manipulators to control formatting, and templatization to allow its use with character types other than char. Standardization in 1998 saw the library moved into the std namespace, and the main header changed from to . It is this standardized version that is covered in the rest of the article. Overview Most of the classes in the library are actually very generalized class templates. Each template can operate on variou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Streams
In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin), standard output (stdout) and standard error (stderr). Originally I/O happened via a physically connected system console (input via keyboard, output via monitor), but standard streams abstract this. When a command is executed via an interactive shell, the streams are typically connected to the text terminal on which the shell is running, but can be changed with redirection or a pipeline. More generally, a child process inherits the standard streams of its parent process. Application Users generally know standard streams as input and output channels that handle data coming from an input device, or that write data from the application. The data may be text with any encoding, or binary data. In many modern systems, the standard error str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluent Interface
In software engineering, a fluent interface is an object-oriented API whose design relies extensively on method chaining. Its goal is to increase code legibility by creating a domain-specific language (DSL). The term was coined in 2005 by Eric Evans and Martin Fowler. Implementation A fluent interface is normally implemented by using method chaining to implement method cascading (in languages that do not natively support cascading), concretely by having each method return the object to which it is attached, often referred to as this or self. Stated more abstractly, a fluent interface relays the instruction context of a subsequent call in method chaining, where generally the context is * Defined through the return value of a called method * Self-referential, where the new context is equivalent to the last context * Terminated through the return of a void context Note that a "fluent interface" means more than just method cascading via chaining; it entails designing an interface t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
"Hello, World!" Program
A "Hello, World!" program is generally a computer program that ignores any input and outputs or displays a message similar to "Hello, World!". A small piece of code in most general-purpose programming languages, this program is used to illustrate a language's basic syntax. "Hello, World!" programs are often the first a student learns to write in a given language, and they can also be used as a sanity check to ensure computer software intended to compile or run source code is correctly installed, and that its operator understands how to use it. History While small test programs have existed since the development of programmable computers, the tradition of using the phrase "Hello, World!" as a test message was influenced by an example program in the 1978 book ''The C Programming Language'', but there is no evidence that it originated there, and it is very likely it was used in BCPL beforehand (as below). The example program in that book prints "", and was inherited from a 1974 ... [...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] |
Constructor (computer Science)
In class-based, object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. A constructor resembles an instance method, but it differs from a method in that it has no explicit return type, it is not implicitly inherited and it usually has different rules for scope modifiers. Constructors often have the same name as the declaring class. They have the task of initializing the object's data members and of establishing the invariant of the class, failing if the invariant is invalid. A properly written constructor leaves the resulting object in a ''valid'' state. Immutable objects must be initialized in a constructor. Most languages allow overloading the constructor in that there can be more than one constructor for a class, with differing parameters. Some languages take consideration of some s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Namespace
In computing, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified. Namespaces are commonly structured as hierarchies to allow reuse of names in different contexts. As an analogy, consider a system of naming of people where each person has a given name, as well as a family name shared with their relatives. If the first names of family members are unique only within each family, then each person can be uniquely identified by the combination of first name and family name; there is only one Jane Doe, though there may be many Janes. Within the namespace of the Doe family, just "Jane" suffices to unambiguously designate this person, while within the "global" namespace of all people, the full name must be used. Prominent examples for namespaces include file systems, which assign names to files. Some programming languages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operator (programming)
In computer programming, operators are constructs defined within programming languages which behave generally like functions, but which differ syntactically or semantically. Common simple examples include arithmetic (e.g. addition with ), comparison (e.g. "greater than" with >), and logical operations (e.g. AND, also written && in some languages). More involved examples include assignment (usually = or :=), field access in a record or object (usually .), and the scope resolution operator (often :: or .). Languages usually define a set of built-in operators, and in some cases allow users to add new meanings to existing operators or even define completely new operators. Syntax Syntactically operators usually contrast to functions. In most languages, functions may be seen as a special form of prefix operator with fixed precedence level and associativity, often with compulsory parentheses e.g. Func(a) (or (Func a) in Lisp). Most languages support programmer-defined ... [...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] |
Stdio
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 streams f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Template (programming)
Templates are a feature of the C++ programming language that allows functions and classes to operate with generic types. This allows a function or class to work on many different data types without being rewritten for each one. The C++ Standard Library provides many useful functions within a framework of connected templates. Major inspirations for C++ templates were the parameterized modules provided by CLU and the generics provided by Ada. Technical overview There are three kinds of templates: ''function templates'', ''class templates'' and, since C++14, ''variable templates''. Since C++11, templates may be either variadic or non-variadic; in earlier versions of C++ they are always non-variadic. Function templates A ''function template'' behaves like a function except that the template can have arguments of many different types (see example). In other words, a function template represents a family of functions. The format for declaring function templates with type para ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order Of Magnitude
An order of magnitude is an approximation of the logarithm of a value relative to some contextually understood reference value, usually 10, interpreted as the base of the logarithm and the representative of values of magnitude one. Logarithmic distributions are common in nature and considering the order of magnitude of values sampled from such a distribution can be more intuitive. When the reference value is 10, the order of magnitude can be understood as the number of digits in the base-10 representation of the value. Similarly, if the reference value is one of some powers of 2, since computers store data in a binary format, the magnitude can be understood in terms of the amount of computer memory needed to store that value. Differences in order of magnitude can be measured on a base-10 logarithmic scale in “decades” (i.e., factors of ten). Examples of numbers of different magnitudes can be found at Orders of magnitude (numbers). Definition Generally, the order of magnitude ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locale (computer Software)
In computing, a locale is a set of parameters that defines the user's language, region and any special variant preferences that the user wants to see in their user interface. Usually a locale identifier consists of at least a language code and a country/region code. Locale is an important aspect of i18n. General locale settings These settings usually include the following display (output) format settings: * Number format setting * Character classification, case conversion settings * Date-time format setting * String collation setting * Currency format setting * Paper size setting * Color setting The locale settings are about formatting output given a locale. So, the time zone information and daylight saving time are not usually part of the locale settings. Less usual is the input format setting, which is mostly defined on a per application basis. Programming and markup language support In these environments, * C * C++ * Eiffel * Java * .NET Framework * REBOL * Ruby * Pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
