• General terms, concepts, and interfaces common to all volumes of this standard, including utility conventions and C-language header definitions, are included in the Base Definitions volume.
• Definitions for system service functions and subroutines, language-specific system services for the C programming language, function issues, including portability, error handling, and error recovery, are included in the System Interfaces volume.
• Definitions for a standard source code-level interface to command interpretation services (a "shell") and common utility programs for application programs are included in the Shell and Utilities volume.
• Extended rationale that did not fit well into the rest of the document structure, which contains historical information concerning the contents of ISO/IEC/IEEE 9945:2009 and why features were included or discarded by the ISO/IEC/IEEE 9945:2009 developers, is included in the Rationale (Informative) volume.

The following areas are outside the scope of ISO/IEC/IEEE 9945:2009:

• graphics interfaces;
• database management system interfaces;
• record I/O considerations;
• object or binary code portability;
• system configuration and resource availability.

ISO/IEC/IEEE 9945:2009 describes the external characteristics and facilities that are of importance to application developers, rather than the internal construction techniques employed to achieve these capabilities. Special emphasis is placed on those functions and facilities that are needed in a wide variety of commercial applications.

This document describes extensions to the C++ Programming Language (Clause 2) that enable operations on source code. These extensions include new syntactic forms and modifications to existing language semantics, as well as changes and additions to the existing library facilities.

Instructions to modify or add paragraphs are written as explicit instructions. Modifications made directly to existing text from ISO/IEC 14882:2020 use underlining to represent added text and strikethrough to represent deleted text.

The International Standard, ISO/IEC 14882:2014, provides important context and specification for this document. This document is written as a set of changes against that specification. Instructions to modify or add paragraphs are written as explicit instructions. Modifications made directly to existing text from the International Standard use underlining to represent added text and strikethrough to represent deleted text.

ISO/IEC 14882 provides important context and specification for this document. This document is written as a set of changes against that specification. Instructions to modify or add paragraphs are written as explicit instructions. Modifications made directly to existing text from ISO/IEC 14882 use underlining to represent added text and strikethrough to represent deleted text.

– The formulation of the foundational and iterator concept requirements using the syntax of the Concepts

TS (2).

– Analogues of the Standard Library algorithms specified in terms of the new concepts.

– The loosening of the algorithm constraints to permit the use of sentinels to denote the end of a range

and corresponding changes to algorithm return types where necessary.

– The addition of new concepts describing range and view abstractions; that is, objects with a begin

iterator and an end sentinel.

– New algorithm overloads that take range objects.

– Support of callable objects (as opposed to function objects) passed as arguments to the algorithms.

– The addition of optional projection arguments to the algorithms to permit on-the-fly data transforma-

tions.

– Analogues of the iterator primitives and new primitives in support of the addition of sentinels to the

library.

– Constrained analogues of the standard iterator adaptors and stream iterators that satisfy the new iterator concepts.

– New iterator adaptors (counted_iterator and common_iterator) and sentinels (unreachable).

Changes to the core language include:

– the extension of the range-based for statement to support the new iterator range requirements (10.4).

ISO/IEC TS 21425:2017 does not specify constrained analogues of other parts of the Standard Library (e.g., the numeric algorithms), nor does it add range support to all the places that could benefit from it (e.g., the containers).

ISO/IEC TS 21425:2017 does not specify any new range views, actions, or facade or adaptor utilities; all are left as future work.

The International Standard, ISO/IEC 14882, provides important context and specification for this Technical Specification. This document is written as a set of changes against that specification. Instructions to modify or add paragraphs are written as explicit instructions. Modifications made directly to existing text from the International Standard use green to represent added text and strikethrough to represent deleted text.

ISO/IEC TS 19841:2015 is non-normative. Some of the functionality described by this Technical Specification may be considered for standardization in a future version of C++, but it is not currently part any C++ standard. Some of the functionality in this Technical Specification may never be standardized, and other functionality may standardized in a substantially changed form.

The goal of this Technical Specification is to build widespread existing practice for Transactional Memory. It gives advice on extensions to those vendors who wish to provide them