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Include Guard
In the C and C++ programming languages, an #include guard, sometimes called a macro guard, header guard or file guard, is a way to avoid the problem of ''double inclusion'' when dealing with the include directive. The C preprocessor processes inclusion directives like #include "Foo.h" to include "Foo.h" and transcludes the code of that file into a copy of the main file often called the translation unit. However, if an #include directive for a given file appears multiple times during compilation, the code will effectively be duplicated in that file. If the included file includes a definition, this can cause a compilation error due to the One Definition Rule, which says that definitions (such as the definition of a class) cannot be duplicated in a translation unit. #include guards prevent this by defining a preprocessor macro when a header is first included. In the event that header file is included a second time, the #include guard will prevent the actual code within that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Naming Conventions (programming)
In computer programming, a naming convention is a set of rules for choosing the character sequence to be used for identifiers which denote variables, types, functions, and other entities in source code and documentation. Reasons for using a naming convention (as opposed to allowing programmers to choose any character sequence) include the following: * To reduce the effort needed to read and understand source code; * To enable code reviews to focus on issues more important than syntax and naming standards. * To enable code quality review tools to focus their reporting mainly on significant issues other than syntax and style preferences. The choice of naming conventions can be a controversial issue, with partisans of each holding theirs to be the best and others to be inferior. Colloquially, this is said to be a matter of dogma. Many companies have also established their own set of conventions. Potential benefits Benefits of a naming convention can include the following: * to p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circular Dependency
In software engineering, a circular dependency is a relation between two or more modules which either directly or indirectly depend on each other to function properly. Such modules are also known as mutually recursive. Overview Circular dependencies are natural in many domain models where certain objects of the same domain depend on each other. However, in software design, circular dependencies between larger software modules are considered an anti-pattern because of their negative effects. Despite this, such circular (or cyclic) dependencies have been found to be widespread among the source files of real-world software. Mutually recursive modules are, however, somewhat common in functional programming, where inductive and recursive definitions are often encouraged. Problems Circular dependencies can cause many unwanted effects in software programs. Most problematic from a software design point of view is the ''tight coupling'' of the mutually dependent modules which reduces o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pragma Once
In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current header file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as #include guards, but with several advantages, including less code, avoidance of name clashes, and sometimes improvement in compilation speed. While #pragma once is available in most modern compilers, its implementation is tricky and might not always be reliable. Modules, introduced in C++20, eliminate the necessity of #pragma once, due to not being handled by the preprocessor. Modules can only be imported at most one time into a translation unit. Example ;File "Grandparent.h" #pragma once struct Foo ; ;File "Parent.h" #include "Grandparent.h" ;File "Child.c" #include "Grandparent.h" #include "Parent.h" In this example, the inclusion of Grandparent.h in both Parent.h and Child.c would ordinarily cause a compilation erro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PL/I
PL/I (Programming Language One, pronounced and sometimes written PL/1) is a procedural, imperative computer programming language initially developed by IBM. It is designed for scientific, engineering, business and system programming. It has been in continuous use by academic, commercial and industrial organizations since it was introduced in the 1960s. A PL/I American National Standards Institute (ANSI) technical standard, X3.53-1976, was published in 1976. PL/I's main domains are data processing, numerical computation, scientific computing, and system programming. It supports recursion, structured programming, linked data structure handling, fixed-point, floating-point, complex, character string handling, and bit string handling. The language syntax is English-like and suited for describing complex data formats with a wide set of functions available to verify and manipulate them. Early history In the 1950s and early 1960s, business and scientific users programmed fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objective-C
Objective-C is a high-level general-purpose, object-oriented programming language that adds Smalltalk-style message passing (messaging) to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTSTEP operating system. Due to Apple macOS’s direct lineage from NeXTSTEP, Objective-C was the standard language used, supported, and promoted by Apple for developing macOS and iOS applications (via their respective application programming interfaces ( APIs), Cocoa and Cocoa Touch) from 1997, when Apple purchased NeXT until the introduction of the Swift language in 2014. Objective-C programs developed for non-Apple operating systems or that are not dependent on Apple's APIs may also be compiled for any platform supported by GNU GNU Compiler Collection (GCC) or LLVM/ Clang. Objective-C source code 'messaging/implementation' program files usually have filename extensions, while Objective-C 'header/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pragma Once
In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current header file to be included only once in a single compilation. Thus, #pragma once serves the same purpose as #include guards, but with several advantages, including less code, avoidance of name clashes, and sometimes improvement in compilation speed. While #pragma once is available in most modern compilers, its implementation is tricky and might not always be reliable. Modules, introduced in C++20, eliminate the necessity of #pragma once, due to not being handled by the preprocessor. Modules can only be imported at most one time into a translation unit. Example ;File "Grandparent.h" #pragma once struct Foo ; ;File "Parent.h" #include "Grandparent.h" ;File "Child.c" #include "Grandparent.h" #include "Parent.h" In this example, the inclusion of Grandparent.h in both Parent.h and Child.c would ordinarily cause a compilation erro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capital Letter
Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally ''majuscule'') and smaller lowercase (more formally '' minuscule'') in the written representation of certain languages. The writing systems that distinguish between the upper- and lowercase have two parallel sets of letters: each in the majuscule set has a counterpart in the minuscule set. Some counterpart letters have the same shape, and differ only in size (e.g. ), but for others the shapes are different (e.g., ). The two case variants are alternative representations of the same letter: they have the same name and pronunciation and are typically treated identically when sorting in alphabetical order. Letter case is generally applied in a mixed-case fashion, with both upper and lowercase letters appearing in a given piece of text for legibility. The choice of case is often denoted by the grammar of a language or by the conventions of a particular discipline. In ortho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Identifier (computer Programming)
In computer programming languages, an identifier is a lexical token (also called a symbol, but not to be confused with the symbol primitive data type) that names the language's entities. Some of the kinds of entities an identifier might denote include variables, data types, labels, subroutines, and modules. Lexical form Which character sequences constitute identifiers depends on the lexical grammar of the language. A common rule is alphanumeric sequences, with underscore also allowed (in some languages, _ is not allowed), and with the condition that it can not begin with a numerical digit (to simplify lexing by avoiding confusing with integer literals) – so foo, foo1, foo_bar, _foo are allowed, but 1foo is not – this is the definition used in earlier versions of C and C++, Python, and many other languages. Later versions of these languages, along with many other modern languages, support many more Unicode characters in an identifier. However, a common restriction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Universally Unique Identifier
A Universally Unique Identifier (UUID) is a 128-bit label used to uniquely identify objects in computer systems. The term Globally Unique Identifier (GUID) is also used, mostly in Microsoft systems. When generated according to the standard methods, UUIDs are, for practical purposes, unique. Their uniqueness does not depend on a central registration authority or coordination between the parties generating them, unlike most other numbering schemes. While the probability that a UUID will be duplicated is not zero, it is generally considered close enough to zero to be negligible. Thus, anyone can create a UUID and use it to identify something with near certainty that the identifier does not duplicate one that has already been, or will be, created to identify something else. Information labeled with UUIDs by independent parties can therefore be later combined into a single database or transmitted on the same channel, with a negligible probability of duplication. Adoption of UUIDs is wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programmer
A programmer, computer programmer or coder is an author of computer source code someone with skill in computer programming. The professional titles Software development, ''software developer'' and Software engineering, ''software engineer'' are used for jobs that require a programmer. Identification Sometimes a programmer or job position is identified by the language used or target platform. For example, assembly language, assembly programmer, web developer. Job title The job titles that include programming tasks have differing connotations across the computer industry and to different individuals. The following are notable descriptions. A ''software developer'' primarily implements software based on specifications and fixes Software bug, bugs. Other duties may include code review, reviewing code changes and software testing, testing. To achieve the required skills for the job, they might obtain a computer science or associate degree, associate degree, attend a Cod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macro (computer Science)
In computer programming, a macro (short for "macro instruction"; ) is a rule or pattern that specifies how a certain input should be mapped to a replacement output. Applying a macro to an input is known as macro expansion. The input and output may be a sequence of lexical tokens or characters, or a syntax tree. Character macros are supported in software applications to make it easy to invoke common command sequences. Token and tree macros are supported in some programming languages to enable code reuse or to extend the language, sometimes for domain-specific languages. Macros are used to make a sequence of computing instructions available to the programmer as a single program statement, making the programming task less tedious and less error-prone. Thus, they are called "macros" because a "big" block of code can be expanded from a "small" sequence of characters. Macros often allow positional or keyword parameters that dictate what the conditional assembler program gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
