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 declaration to reference via a generic variable another different class without creating full declaration for each of these different classes.
Generic programming is a style of computer programming in which algorithms are written in terms of data types to-be-specified-later that are then instantiated when needed for specific types provided as parameters. This approach, pioneered in the programming language ML in 1973, permits writing common functions or data types that differ only in the set of types on which they operate when used, thus reducing duplicate code.
Template metaprogramming (TMP) is a metaprogramming technique in which templates are used by a compiler to generate temporary source code, which is merged by the compiler with the rest of the source code and then compiled. The output of these templates can include compile-time constants, data structures, and complete functions. The use of templates can be thought of as compile-time polymorphism. The technique is used by a number of languages, the best-known being C++, but also Curl, D, Nim, and XL.
In mathematics and computer science, a higher-order function (HOF) is a function that does at least one of the following:
The syntax of the C programming language is the set of rules governing writing of software in C. It is designed to allow for programs that are extremely terse, have a close relationship with the resulting object code, and yet provide relatively high-level data abstraction. C was the first widely successful high-level language for portable operating-system development.
In mathematics and in computer programming, a variadic function is a function of indefinite arity, i.e., one which accepts a variable number of arguments. Support for variadic functions differs widely among programming languages.
In some programming languages, const is a type qualifier that indicates that the data is read-only. While this can be used to declare constants, const in the C family of languages differs from similar constructs in other languages in that it is part of the type, and thus has complicated behavior when combined with pointers, references, composite data types, and type-checking. In other languages, the data is not in a single memory location, but copied at compile time for each use. Languages which use it include C, C++, D, JavaScript, Julia, and Rust.
The One Definition Rule (ODR) is an important rule of the C++ programming language that prescribes that classes/structs and non-inline functions cannot have more than one definition in the entire program and templates and types cannot have more than one definition by translation unit. It is defined in the ISO C++ Standard 2003, at section 3.2. Some other programming languages have similar but differently defined rules towards the same objective.
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.
A class in C++ is a user-defined type or data structure declared with any of the keywords class, struct or union that has data and functions as its members whose access is governed by the three access specifiers private, protected or public. By default access to members of a C++ class declared with the keyword class is private. The private members are not accessible outside the class; they can be accessed only through member functions of the class. The public members form an interface to the class and are accessible outside the class.
sizeof is a unary operator in the C and C++ programming languages that evaluates to the storage size of an expression or a data type, measured in units sized as char. Consequently, the expression sizeof(char) evaluates to 1. The number of bits of type char is specified by the preprocessor macro CHAR_BIT, defined in the standard include file limits.h. On most modern computing platforms this is eight bits. The result of sizeof is an unsigned integer that is usually typed as size_t.
The C and C++ programming languages are closely related but have many significant differences. C++ began as a fork of an early, pre-standardized C, and was designed to be mostly source-and-link compatible with C compilers of the time. Due to this, development tools for the two languages are often integrated into a single product, with the programmer able to specify C or C++ as their source language.
The curiously recurring template pattern (CRTP) is an idiom, originally in C++, in which a class X derives from a class template instantiation using X itself as a template argument. More generally it is known as F-bound polymorphism, and it is a form of F-bounded quantification.
C++11 is a version of a joint technical standard, ISO/IEC 14882, by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), for the C++ programming language. C++11 replaced the prior version of the C++ standard, named C++03, and was later replaced by C++14. The name follows the tradition of naming language versions by the publication year of the specification, though it was formerly named C++0x because it was expected to be published before 2010.
Substitution failure is not an error (SFINAE) is a principle in C++ where an invalid substitution of template parameters is not in itself an error. David Vandevoorde first introduced the acronym SFINAE to describe related programming techniques.
Expression templates are a C++ template metaprogramming technique that builds structures representing a computation at compile time, where expressions are evaluated only as needed to produce efficient code for the entire computation. Expression templates thus allow programmers to bypass the normal order of evaluation of the C++ language and achieve optimizations such as loop fusion.
In computer programming, variadic templates are templates that take a variable number of arguments.
"typename" is a keyword in the C++ programming language used when writing templates. It is used for specifying that a dependent name in a template definition or declaration is a type. In the original C++ compilers before the first ISO standard was completed, the typename keyword was not part of the C++ language and Bjarne Stroustrup used the class keyword for template arguments instead. While typename is now the preferred keyword, older source code may still use the class keyword instead.
C++14 is a version of the ISO/IEC 14882 standard for the C++ programming language. It is intended to be a small extension over C++11, featuring mainly bug fixes and small improvements, and was replaced by C++17. Its approval was announced on August 18, 2014. C++14 was published as ISO/IEC 14882:2014 in December 2014.
In computer programming, a subroutine will often inform calling code about the result of its computation, by returning a value to that calling code. The data type of that value is called the function's return type.
