The first edition of ISO/IEC was published in A technical corrigendum was approved in ,. and the standard was published. ISO/IEC JTC1 SC22 WG21 N Date: ISO/IEC CD ISO/ IEC JTC1 SC Secretariat: ANSI C C++ and ISO C++ Download Citation on ResearchGate | On Jan 1, , ISO and others published ISOslash IEC Programming languages C++ }.
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It has imperativeobject-oriented and generic programming features, while also providing facilities for low-level memory manipulation.
It was designed with a bias toward system programming and embeddedresource-constrained and large systems, with performanceefficiency and flexibility of use as its design highlights. Stroustrup found that Simula had features that were very helpful for large software development, but the language was too slow for practical use, while BCPL was fast but too low-level to be suitable for large software development.
Initially, Stroustrup’s “C with Classes” added features to the C compiler, Cpre, including classesderived classesstrong typinginlining and default arguments. This work became the basis for the future standard. Later feature additions included templatesexceptionsnamespacesnew castsand a boolean type.
When Mascitti was questioned informally in about the naming, he indicated that it was given in a tongue-in-cheek spirit. As part of the standardization process, ISO also publishes technical reports and specifications:.
More technical specifications are in development and pending approval, including concurrency library extensions, a networking standard library, ranges, and modules. Doing it efficiently is what distinguishes it from other languages”. Static storage duration objects are created before main is entered see exceptions below and destroyed in reverse order of creation after main exits. The exact order of creation is not specified by the standard though there are some rules defined below to allow implementations some freedom in how to organize their implementation.
More formally, objects of this type have a lifespan that “shall last for the duration of the program”. Static storage duration objects are initialized in two phases. First, “static initialization” is performed, and only after all static initialization is performed, “dynamic initialization” is performed. In static initialization, all objects are first initialized with zeros; after that, all objects that have a constant initialization phase are initialized with the constant expression i. Though it is not specified in the standard, the static initialization phase can be completed at compile time and saved in the data partition of the executable.
The dynamic initialization order is defined as the order of declaration within the compilation unit i. No guarantees are provided about the order of initialization between compilation units. Variables of this type are very similar to static storage duration objects. The main difference is the creation time is just prior to thread creation and destruction is done after the thread has been joined.
They are created and potentially initialized at the point of declaration see below for details and destroyed in the reverse order of creation when the scope is left. This is implemented by allocation on the stack. Local variables are created as the point of execution passes the declaration point.
If the variable has a constructor or initializer this is used to define the initial state of the object. Local variables are destroyed when the local block or function that they are declared in is closed. Member variables are created when 14882 parent object is created. Array members are initialized from 0 to the last member of the array in order. Member variables oec destroyed when the parent object is destroyed in the reverse order of creation.
If the parent is an “automatic object” then it will be destroyed when it goes out of scope which triggers the destruction of all its members. Temporary variables are created as the result of expression evaluation and are destroyed when the statement containing the expression has been fully evaluated usually at the ; at the end of a statement.
These objects have a dynamic lifespan and are created with a call to new and destroyed explicitly with a call to delete. Templates may be parameterized by types, compile-time constants, and other templates. Templates are implemented by instantiation at compile-time. To instantiate a template, compilers substitute specific arguments for a template’s parameters to generate a concrete function or class instance. Some substitutions are not possible; these are eliminated by an overload resolution policy described by the phrase ” Substitution failure is not an error ” SFINAE.
Templates are a powerful tool that can be used for generic programmingtemplate metaprogrammingand code optimization, but this power implies a cost. Template use may increase code size, because each template instantiation produces a copy of the template code: Templates are different from macros: Templates are aware of the semantics and type system of their companion language, as well as all compile-time type definitions, and can perform high-level operations including programmatic flow control based on evaluation of strictly type-checked parameters.
In other words, macros can control compilation flow based on pre-defined symbols but cannot, unlike templates, independently instantiate new symbols.
Templates are a tool for static polymorphism see below and generic programming. In summary, a template is a compile-time parameterized function or class written without knowledge of the specific arguments used to instantiate it. After instantiation, the resulting code is equivalent to code written specifically for the passed arguments.
In this manner, templates provide a way to decouple generic, broadly applicable aspects of functions and classes encoded in templates from specific aspects encoded in template parameters without sacrificing performance due to abstraction. Encapsulation is the hiding of information to ensure that data structures and operators are used as intended and to make the usage model more obvious to the developer. Within a class, members can be declared as either public, protected, 0203 private to explicitly enforce encapsulation.
A public member of the class is accessible to any function. A private member is accessible only to functions that are members of that class and to functions and classes explicitly granted access permission by the class “friends”. A protected member is accessible to members of classes that inherit from the class in addition to the class itself and any friends. The object-oriented principle ensures ifc encapsulation of all and only the functions that access the internal representation of a type.
Programmers can declare parts or all of the representation of a type to be public, and they are allowed to make public entities not part of the representation of a type. It is generally considered good practice to make all data private or protected, and to make public only those functions that are part of a minimal interface for users of the class.
This can hide the details of data implementation, allowing the designer to later fundamentally change the implementation without changing the interface in any way. Inheritance allows one data type jec acquire properties of other data types.
Inheritance from a base class may be declared as public, protected, or private. This access specifier determines whether unrelated and derived classes can access the inherited public and protected members of the base class.
Only public inheritance corresponds to what is usually meant by “inheritance”.
The other two forms are much less frequently used. If the access specifier is omitted, a “class” inherits privately, while a “struct” inherits publicly.
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Base classes may be declared as virtual; this is called virtual inheritance. Virtual inheritance ensures that only one instance of a base class exists in the inheritance graph, avoiding some of the ambiguity problems of 1482 inheritance. Some other languages, such ic C or Javaaccomplish something similar although more limited by allowing inheritance of multiple interfaces while restricting the number of base 200 to one interfaces, unlike classes, provide only declarations of member functions, no implementation or member data.
The member functions of such an abstract base class are normally explicitly defined in the derived class, not inherited implicitly. Almost all operators can be overloaded for user-defined types, with a few notable exceptions such as member access. Overloading an operator does not change the precedence of calculations involving the operator, nor does it change the number of operands that the operator uses any operand may however be ignored by the operator, though it will be evaluated prior to oec.
Polymorphism enables one common interface for many implementations, and for objects to act differently under different circumstances. Compile-time polymorphism does not allow for certain run-time decisions, while runtime polymorphism typically incurs a performance penalty.
Intel C++ Composer conformance to ISO/IEC 14882:2003
Function overloading allows programs to declare multiple functions having the same name but with different arguments i. The functions are distinguished by the number or types of their formal parameters. Thus, the same function name can refer to different functions depending on the context in which it is used. The type returned by the function is not used to distinguish overloaded functions and would result in a compile-time error message.
When declaring a function, a programmer can specify for one or more parameters a default value. Doing so allows the parameters with defaults to optionally be omitted when the function is called, in which case the default arguments will be used. When a function is called with fewer arguments than there are declared parameters, explicit arguments are matched to parameters in left-to-right order, with any unmatched parameters at the end of the parameter list being assigned their default arguments.
In many cases, specifying default arguments in a single function declaration is preferable to providing overloaded function definitions with different numbers of parameters.
In particular, through the curiously recurring template patternit’s possible to implement a form of static polymorphism that closely mimics the syntax for overriding virtual functions. Contrary to some opinion, template code will not generate a bulk code after compilation with the proper compiler settings.
This allows arrays and other kinds of containers to hold pointers to objects of differing types references cannot be directly held in containers. This enables dynamic run-time polymorphism, where the referred objects can behave differently depending on their actual, derived types. The attempt is necessary as often one does not know which derived type is referenced.
Ordinarily, when a function in a derived class overrides a function in a base class, the function to call is determined by the type of the object. A given function is overridden when there exists no difference in the number or type of parameters between two or more definitions of that function. Hence, at compile time, it may not be possible to determine the type of the object and therefore the correct function to call, given only a base class pointer; the decision is therefore put off until runtime.
This is called dynamic dispatch. Virtual member functions or methods  allow the most specific implementation of the function to be called, according to the actual run-time type of the object. If the object type is known, this may be bypassed by prepending a fully qualified class name before the function call, but in general calls to virtual functions are resolved at run time.
In addition to standard member functions, operator overloads and destructors can be virtual. As a rule of thumb, if any function in the class is virtual, the destructor should be as well.
C++ – Standards
As the type of an object at its creation is known at compile time, constructors, and by extension copy constructors, cannot be virtual. Nonetheless a situation may arise where a copy of an object needs to be created when a pointer to a derived object is passed as a pointer to a base object. In such a case, a common solution is to create a clone or similar virtual function that creates and returns a copy of the derived class when called.
A class containing a pure virtual function is called an abstract class. Objects cannot be created from an abstract class; they can only be derived from.
Any derived class inherits the virtual function as pure and must provide a non-pure definition of it and all other pure virtual functions before objects of the derived class can be created. A program that attempts to create an object of a class with a pure virtual member function or inherited pure virtual member function is ill-formed. The [capture] list supports the definition of closures. Such lambda expressions are defined in the standard as syntactic sugar for an unnamed function object.
An example lambda function may be defined as follows:.