Most Vexing Parse
The most vexing parse is a counterintuitive form of syntactic ambiguous grammar, ambiguity resolution in the C++ programming language. In certain situations, the C++ grammar cannot distinguish between the Initialization (programming), creation of an object Parameter (computer programming), parameter and Type declaration, specification of a function's type. In those situations, the compiler is required to interpret the line as the latter. Occurrence The term "most vexing parse" was first used by Scott Meyers in his 2001 book ''Effective STL''. While unusual in C (programming language), C, the phenomenon was quite common in C++ until the introduction of uniform initialization in C++11. Examples C-style casts A simple example appears when a functional cast is intended to convert an expression for initializing a variable: void f(double my_dbl) Line 2 above is ambiguous. One possible interpretation is to declare a Variable (computer science), variable i with initial value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ambiguous Grammar
In computer science, an ambiguous grammar is a context-free grammar for which there exists a string (computer science), string that can have more than one leftmost derivation or parse tree. Every non-empty context-free language admits an ambiguous grammar by introducing e.g. a duplicate rule. A language that only admits ambiguous grammars is called an #Inherently ambiguous languages, inherently ambiguous language. Deterministic context-free grammars are always unambiguous, and are an important subclass of unambiguous grammars; there are non-deterministic unambiguous grammars, however. For computer programming languages, the reference grammar is often ambiguous, due to issues such as the dangling else problem. If present, these ambiguities are generally resolved by adding precedence rules or other context-sensitive grammar, context-sensitive parsing rules, so the overall phrase grammar is unambiguous. Some parsing algorithms (such as Earley parser, Earley or Generalized LR parser, GL ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Function Declaration
In computer programming, a function prototype is a declaration of a function that specifies the function's name and type signature (arity, data types of parameters, and return type), but omits the function body. While a function definition specifies ''how'' the function does what it does (the "implementation"), a function prototype merely specifies its interface, i.e. ''what'' data types go in and come out of it. The term "function prototype" is particularly used in the context of the programming languages C and C++ where placing forward declarations of functions in header files allows for splitting a program into translation units, i.e. into parts that a compiler can separately translate into object files, to be combined by a linker into an executable or a library. The function declaration precedes the function definition, giving details of name, return type, and storage class along with other relevant attributes. Function prototypes can be used when either: * Defining ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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C++17
C17, C-17 or C.17 may refer to: Transportation * , a 1917 British C-class submarine Air * Boeing C-17 Globemaster III, a military transport aircraft * Lockheed Y1C-17 Vega, a six-passenger monoplane * Cierva C.17, a 1928 English experimental autogyro Land * C-17 highway (Spain) also known as ''Eix del Congost'', a primary highway in Catalonia * Queensland C17 class locomotive * Sauber C17, a 1998 Formula One car Science and technology * C17 (C standard revision), an informal name for ISO/IEC 9899:2018, a revision of the C programming language * C17, a female two-pole IEC 60320 electrical cable connector that mates with a male C18 appliance inlet * Caldwell 17, a dwarf spheroidal galaxy of the Local Group in the constellation Cassiopeia * Carbon-17 (C-17 or 17C), an isotope of carbon * C17, a 17-Carbon molecule in chlorophyll metabolism ** Precorrin-3B C17-methyltransferase, an enzyme involved in that metabolism * Small intestine cancer (ICD-10 code) Other uses * Ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Optimizing Compiler
An optimizing compiler is a compiler designed to generate code that is optimized in aspects such as minimizing program execution time, memory usage, storage size, and power consumption. Optimization is generally implemented as a sequence of optimizing transformations, a.k.a. compiler optimizations algorithms that transform code to produce semantically equivalent code optimized for some aspect. Optimization is limited by a number of factors. Theoretical analysis indicates that some optimization problems are NP-complete, or even undecidable. Also, producing perfectly ''optimal'' code is not possible since optimizing for one aspect often degrades performance for another. Optimization is a collection of heuristic methods for improving resource usage in typical programs. Categorization Local vs. global scope Scope describes how much of the input code is considered to apply optimizations. Local scope optimizations use information local to a basic block. Since basic blocks cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Copy Constructor (C++)
Copy may refer to: *Copying or the product of copying (including the plural "copies"); the duplication of information or an artifact **Cut, copy and paste, a method of reproducing text or other data in computing ** File copying **Photocopying, a process which makes paper copies of documents and other visual images ** Fax, a telecommunications technology used to transfer facsimile copies of documents, especially over the telephone network ** Facsimile, a copy or reproduction that is as true to the original source as possible **Replica, a copy closely resembling the original concerning its shape and appearance **Term of art in U.S. copyright law meaning a material object in which a work of authorship has been embodied, such as a book * Copy (command), a shell command on DOS and Windows systems * Copy (publishing), written content in publications, in contrast to photographs or other elements of layout. **The output of journalists and authors, ready for copy editing and typesetting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Pointer (computer Programming)
In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer ''references'' a location in memory, and obtaining the value stored at that location is known as ''dereferencing'' the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture. Using pointers significantly improves performance for repetitive operations, like traversing iterable data structures (e.g. strings, lookup tables, control tables, linked lists, and tree structures). In particular, it is often much cheaper in time and space to copy and deref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Reference (C++)
A reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. It is called a ''name'' for the second object. The next object, the one to which the first object refers, is called the ''referent'' of the first object. A name is usually a phrase or expression, or some other symbolic representation. Its referent may be anything – a material object, a person, an event, an activity, or an abstract concept. References can take on many forms, including: a thought, a sensory perception that is audible (onomatopoeia), visual (text), olfactory, or tactile, emotional state, relationship with other, spacetime coordinates, symbolic or alpha-numeric, a physical object, or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in cryptography. References feature in ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Typedef
typedef is a reserved keyword in the programming languages C, C++, and Objective-C. It is used to create an additional name (''alias'') for another data type, but does not create a new type, except in the obscure case of a qualified typedef of an array type where the typedef qualifiers are transferred to the array element type. As such, it is often used to simplify the syntax of declaring complex data structures consisting of struct and union types, although it is also commonly used to provide specific descriptive type names for integer data types of varying sizes. Syntax A ''typedef declaration'' follows the same syntax as declaring any other C identifier. The keyword typedef itself is a specifier which means that while it typically appears at the start of the declaration, it can also appear after the type specifiers or between two of them. In the C standard library and in POSIX specifications, the identifier for the typedef definition is often suffixed with , such as in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Clang++
Clang () is a compiler front end for the programming languages C, C++, Objective-C, Objective-C++, and the software frameworks OpenMP, OpenCL, RenderScript, CUDA, SYCL, and HIP. It acts as a drop-in replacement for the GNU Compiler Collection (GCC), supporting most of its compiling flags and unofficial language extensions. It includes a static analyzer, and several code analysis tools. Clang operates in tandem with the LLVM compiler back end and has been a subproject of LLVM 2.6 and later. As with LLVM, it is free and open-source software under the Apache 2.0 software license. Its contributors include Apple, Microsoft, Google, ARM, Sony, Intel, and AMD. Clang 17, the latest major version of Clang as of October 2023, has full support for all published C++ standards up to C++17, implements most features of C++20, and has initial support for the C++23 standard. Since v16.0.0, Clang compiles C++ using the GNU++17 dialect by default, which includes features from the C++17 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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C++ Standard
C standard may refer to: * ANSI C, C99, C11, C17, or C23, specifications of the C programming language * C standard library The C standard library, sometimes referred to as libc, is the standard library for the C (programming language), C programming language, as specified in the ISO C standard.International Organization for Standardization, ISO/International Electrote ... * C tuning (guitar), a type of tuning for guitars {{Disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Function Object
In computer programming, a function object is a construct allowing an object (computer science), object to be invoked or called as if it were an ordinary subroutine, function, usually with the same syntax (a function parameter that can also be a function). In some languages, particularly C++, function objects are often called functors (not related to Functor (functional programming), the functional programming concept). Description A typical use of a function object is in writing callback (computer science), callback functions. A callback in procedural programming, procedural languages, such as C (programming language), C, may be performed by using function pointers. However it can be difficult or awkward to pass a state into or out of the callback function. This restriction also inhibits more dynamic behavior of the function. A function object solves those problems since the function is really a facade pattern, façade for a full object, carrying its own state. Many modern (an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Variable (programming)
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 Data (computer science), data or Object (computer science), object 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 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 R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |