C++ is standardized by theInternational Organization for Standardization (ISO), with the latest standard version ratified and published by ISO in October 2024 asISO/IEC 14882:2024 (informally known asC++23).[17] The C++ programming language was initially standardized in 1998 asISO/IEC 14882:1998, which was then amended by theC++03,C++11,C++14,C++17, andC++20 standards. The currentC++23 standard supersedes these with new features and an enlargedstandard library. Before the initial standardization in 1998, C++ was developed by Stroustrup atBell Labs since 1979 as an extension of the C language; he wanted an efficient and flexible language similar to C that also providedhigh-level features for program organization.[18] Since 2012, C++ has been on a three-year release schedule[19] withC++26 as the next planned standard.[20]
In 1979,Bjarne Stroustrup, a Danishcomputer scientist, began work on "C withClasses", the predecessor to C++.[21] The motivation for creating a new language originated from Stroustrup's experience in programming for his PhD thesis. Stroustrup found thatSimula had features that were very helpful for large software development, but the language was too slow for practical use, whileBCPL was fast but too low-level to be suitable for large software development. When Stroustrup started working inAT&T Bell Labs, he had the problem of analyzing theUNIXkernel with respect todistributed computing. Remembering his PhD experience, Stroustrup set out to enhance theC language with Simula-like features.[22] C was chosen because it was general-purpose, fast, portable, and widely used. In addition to C and Simula's influences, other languages influenced this new language, includingALGOL 68,Ada,CLU, andML.[citation needed]
A quiz on C++11 features being given in Paris in 2015
In 1982, Stroustrup started to develop a successor to C with Classes, which he named "C++" (++ being theincrement operator in C) after going through several other names. New features were added, includingvirtual functions, function andoperator overloading,references, constants, type-safe free-store memory allocation (new/delete), improved type checking, and BCPL-style single-line comments with two forward slashes (//). Furthermore, Stroustrup developed a new, standalone compiler for C++,Cfront.
In 1984, Stroustrup implemented the first stream input/output library. The idea of providing an output operator rather than a named output function was suggested byDoug McIlroy[2] (who had previously suggestedUnix pipes).
In 1985, the first edition ofThe C++ Programming Language was released, which became the definitive reference for the language, as there was not yet an official standard.[24] The first commercial implementation of C++ was released in October of the same year.[21]
In 1989, C++ 2.0 was released, followed by the updated second edition ofThe C++ Programming Language in 1991.[25] New features in 2.0 included multiple inheritance, abstract classes, static member functions,const member functions, and protected members. In 1990,The Annotated C++ Reference Manual was published. This work became the basis for the future standard. Later feature additions includedtemplates,exceptions,namespaces, newcasts, and aBoolean type.
In 1998, C++98 was released, standardizing the language, and a minor update (C++03) was released in 2003.
After C++98, C++ evolved relatively slowly until, in 2011, theC++11 standard was released, adding numerous new features, enlarging the standard library further, and providing more facilities to C++ programmers. After a minorC++14 update released in December 2014, various new additions were introduced inC++17.[26] After becoming finalized in February 2020,[27] a draft of the C++20 standard was approved on 4 September 2020, and officially published on 15 December 2020.[28][29]
On January 3, 2018, Stroustrup was announced as the 2018 winner of theCharles Stark Draper Prize for Engineering, "for conceptualizing and developing the C++ programming language".[30]
In December 2022, C++ ranked third on theTIOBE index, surpassingJava for the first time in the history of the index. As of November 2024[update], the language ranks second afterPython, with Java being in third.[31]
In March 2025, Stroustrup issued a call for the language community to defend it. Since the language allows manual memory management, bugs that represent security risks such asbuffer overflow may be introduced in programs when inadvertently misused by the programmer.[32]
According to Stroustrup, "the name signifies the evolutionary nature of the changes from C."[33] This name is credited to Rick Mascitti (mid-1983)[23] and was first used in December 1983. When Mascitti was questioned informally in 1992 about the naming, he indicated that it was given in atongue-in-cheek spirit. The name comes from C's++operator (whichincrements thevalue of avariable) and a commonnaming convention of using "+" to indicate an enhanced computer program.
During C++'s development period, the language had been referred to as "new C" and "C with Classes"[23][34] before acquiring its final name.
Throughout C++'s life, its development and evolution has been guided by a set of principles:[22]
It must be driven by actual problems and its features should be immediately useful in real world programs.
Every feature should be implementable (with a reasonably obvious way to do so).
Programmers should be free to pick their own programming style, and that style should be fully supported by C++.
Allowing a useful feature is more important than preventing every possible misuse of C++.
It should provide facilities for organizing programs into separate, well-defined parts, and provide facilities for combining separately developed parts.
No implicit violations of thetype system (but allow explicit violations; that is, those explicitly requested by the programmer).
User-created types need to have the same support and performance as built-in types.
Unused features should not negatively impact created executables (e.g. in lower performance).
C++ is standardized by anISO working group known asJTC1/SC22/WG21. The working group holds three week-long meetings each year.[41] So far, it has published seven revisions of the C++ standard and is currently working on the next revision,C++26.
Scene during the C++ standards committee meeting in Stockholm in 1996
In 1998, the ISO working group standardized C++ for the first time asISO/IEC 14882:1998, which is informally known asC++98. In 2003, it published a new version of the C++ standard calledISO/IEC 14882:2003, which fixed problems identified in C++98.
The next major revision of the standard was informally referred to as "C++0x", but it was not released until 2011.[42]C++11 (14882:2011) included many additions to both the core language and the standard library.[37]
In 2014,C++14 (also known as C++1y) was released as a small extension to C++11, featuring mainly bug fixes and small improvements.[43] The Draft International Standard ballot procedures completed in mid-August 2014.[44]
After C++14, a major revisionC++17, informally known as C++1z, was completed by the ISO C++ committee in mid July 2017 and was approved and published in December 2017.[45]
The C++ language has two main components: a direct mapping of hardware features provided primarily by the C subset, and zero-overhead abstractions based on those mappings. Stroustrup describes C++ as "a light-weight abstraction programming language [designed] for building and using efficient and elegant abstractions";[15] and "offering both hardware access and abstraction is the basis of C++. Doing it efficiently is what distinguishes it from other languages."[65]
The C++standard consists of two parts: the core language and the standard library. C++ programmers expect the latter on every major implementation of C++; it includes aggregate types (vectors,linked lists, maps (such astree maps andhash maps), sets (such astree sets andhash sets),queues,stacks,arrays,tuples),algorithms (find,for_each,binary_search,random_shuffle, etc.), input/output facilities (I/O streams, for reading from and writing to the console and files),file system manipulation, localisation support,smart pointers for automatic memory management,regular expression support,multi-threading library, atomics support (allowing a variable to be read or written to by at most one thread at a time without any external synchronisation), time utilities (measurement, getting current time, etc.), a system for converting error reporting that does not use C++exceptions into C++ exceptions,random number generators, and a slightly modified version of theC standard library (to make it comply with the C++ type system).
The design of the C++ standard library, much like the C standard library, is minimalistic, and contains only core features for programming, lacking most of the more specialised features offered by theJava standard library orC# standard library. For more features, some third-party libraries such asBoost libraries andPOCO C++ Libraries, which offer additional features, may be used to supplement the standard library.
A large part of the C++ library is based on theStandard Template Library (STL). Useful tools provided by the STL includecontainers as the collections of objects (such asvectors andlists),iterators that provide array-like access to containers, andalgorithms that perform operations such as searching and sorting.
Furthermore, (multi)maps (associative arrays) and (multi)sets are provided, all of which export compatible interfaces. Therefore, using templates it is possible to write generic algorithms that work with any container or on any sequence defined by iterators.
As in C, thefeatures of thelibrary may be accessed by using the#includedirective to include astandard header. TheC++ Standard Library provides 105 standard headers, of which 27 are deprecated. With the introduction ofmodules inC++20, these headers may be accessed withimport, and inC++23, the entire standard library can now be directly imported as module itself, withimportstd;. Currently, the C++ standard library provides two modules,std andstd.compat (a compatibility module forstd which exports C standard library facilities into the global namespace).
The standard incorporates the STL that was originally designed byAlexander Stepanov, who experimented with generic algorithms and containers for many years. When he started with C++, he finally found a language where it was possible to create generic algorithms (e.g., STL sort) that perform even better than, for example, the C standard library qsort, thanks to C++ features like using inlining and compile-time binding instead of function pointers. The standard does not refer to it as "STL", as it is merely a part of the standard library, but the term is still widely used to distinguish it from the rest of the standard library (input/output streams, internationalization, diagnostics, the C library subset, etc.).[68]
Most C++ compilers, and all major ones, provide a standards-conforming implementation of the C++ standard library.
The C++ Core Guidelines[69] are an initiative led by Bjarne Stroustrup, the inventor of C++, and Herb Sutter, the convener and chair of the C++ ISO Working Group, to help programmers write 'Modern C++' by using best practices for the language standards C++11 and newer, and to help developers of compilers and static checking tools to create rules for catching bad programming practices.
The main aim is to efficiently and consistently write type and resource safe C++.
The Core Guidelines were announced[70] in the opening keynote at CPPCon 2015.
The Guidelines are accompanied by the Guideline Support Library (GSL),[71] a header only library of types and functions to implement the Core Guidelines and static checker tools for enforcing Guideline rules.[72]
To give compiler vendors greater freedom, the C++ standards committee decided not to dictate the implementation ofname mangling,exception handling, and other implementation-specific features. The downside of this decision is thatobject code produced by differentcompilers is expected to be incompatible. There are, however, attempts to standardize compilers for particular machines oroperating systems. For example, the Itanium C++ ABI is processor-independent (despite its name) and is implemented by GCC and Clang.[73]
C++ is often considered to be a superset ofC but this is not strictly true.[74] Most C code can easily be made to compile correctly in C++ but there are a few differences that cause some valid C code to be invalid or behave differently in C++. For example, C allows implicit conversion fromvoid* to other pointer types but C++ does not (for type safety reasons). Also, C++ defines many new keywords, such asnew andclass, which may be used as identifiers (for example, variable names) in a C program.
Some incompatibilities have been removed by the 1999 revision of the C standard (C99), which now supports C++ features such as line comments (//) and declarations mixed with code. On the other hand, C99 introduced a number of new features that C++ did not support that were incompatible or redundant in C++, such asvariable-length arrays, native complex-number types (however, thestd::complex class in the C++ standard library provides similar functionality, although not code-compatible), designated initializers,compound literals, and therestrict keyword.[75] Some of the C99-introduced features were included in the subsequent version of the C++ standard,C++11 (out of those which were not redundant).[76][77][78] However, the C++11 standard introduces new incompatibilities, such as disallowing assignment of a string literal to a character pointer, which remains valid C.
To intermix C and C++ code, any function declaration or definition that is to be called from/used both in C and C++ must be declared with C linkage by placing it within anextern"C"{/*...*/} block. Such a function may not rely on features depending onname mangling (i.e., function overloading).
Programs developed in C or C++ often utilize inline assembly to take advantage of its low-level functionalities, greater speed, and enhanced control compared to high-level programming languages[79][80] when optimizing for performance is essential. C++ provides support for embeddingassembly language using asm declarations,[81] but the compatibility ofinline assembly varies significantly betweencompilers and architectures. Unlike high-level language features such asPython orJava, assembly code is highly dependent on the underlying processor and compiler implementation.
Different C++ compilers implement inline assembly in distinct ways.
GCC (GNU Compiler Collection) andClang:[82] Use the GCC extended inline assembly syntax. Using__asm__ keyword instead ofasm when writing code that can be compiled with-ansi and-std options, which allows specifying input/output operands and clobbered registers. This approach is widely adopted, including by Intel[83] and IBM[84] compilers.
MSVC (Microsoft Visual C++): The inline assembler is built into the compiler. Previously supported inline assembly via the__asm keyword, but this support has been removed in 64-bit mode, requiring separate .asm modules instead.[85]
TI ARM Clang and Embedded Compilers:[86] Some embedded system compilers, like Texas Instruments' TI Arm Clang, allow inline assembly but impose stricter rules to avoid conflicts with register conventions and calling conventions.
^This code is adapted from Bjarne Stroustrup's errata page (p. 633). He addresses the use of'\n' rather thanstd::endl. Also seeCan I write "void main()"?Archived 2 July 2020 at theWayback Machine for an explanation of the implicitreturn 0; in themain function. This implicit return isnot available in other functions.
^Naugler, David (May 2007). "C# 2.0 for C++ and Java programmer: conference workshop".Journal of Computing Sciences in Colleges.22 (5).Although C# has been strongly influenced by Java it has also been strongly influenced by C++ and is best viewed as a descendant of both C++ and Java.
Standard C++ Foundation – a non-profit organization that promotes the use and understanding of standard C++.Bjarne Stroustrup is a director of the organization.
