Skip to main content
Redhat Developers  Logo
  • Products

    Featured

    • Red Hat Enterprise Linux
      Red Hat Enterprise Linux Icon
    • Red Hat OpenShift AI
      Red Hat OpenShift AI
    • Red Hat Enterprise Linux AI
      Linux icon inside of a brain
    • Image mode for Red Hat Enterprise Linux
      RHEL image mode
    • Red Hat OpenShift
      Openshift icon
    • Red Hat Ansible Automation Platform
      Ansible icon
    • Red Hat Developer Hub
      Developer Hub
    • View All Red Hat Products
    • Linux

      • Red Hat Enterprise Linux
      • Image mode for Red Hat Enterprise Linux
      • Red Hat Universal Base Images (UBI)
    • Java runtimes & frameworks

      • JBoss Enterprise Application Platform
      • Red Hat build of OpenJDK
    • Kubernetes

      • Red Hat OpenShift
      • Microsoft Azure Red Hat OpenShift
      • Red Hat OpenShift Virtualization
      • Red Hat OpenShift Lightspeed
    • Integration & App Connectivity

      • Red Hat Build of Apache Camel
      • Red Hat Service Interconnect
      • Red Hat Connectivity Link
    • AI/ML

      • Red Hat OpenShift AI
      • Red Hat Enterprise Linux AI
    • Automation

      • Red Hat Ansible Automation Platform
      • Red Hat Ansible Lightspeed
    • Developer tools

      • Red Hat Trusted Software Supply Chain
      • Podman Desktop
      • Red Hat OpenShift Dev Spaces
    • Developer Sandbox

      Developer Sandbox
      Try Red Hat products and technologies without setup or configuration fees for 30 days with this shared Openshift and Kubernetes cluster.
    • Try at no cost
  • Technologies

    Featured

    • AI/ML
      AI/ML Icon
    • Linux
      Linux Icon
    • Kubernetes
      Cloud icon
    • Automation
      Automation Icon showing arrows moving in a circle around a gear
    • View All Technologies
    • Programming Languages & Frameworks

      • Java
      • Python
      • JavaScript
    • System Design & Architecture

      • Red Hat architecture and design patterns
      • Microservices
      • Event-Driven Architecture
      • Databases
    • Developer Productivity

      • Developer productivity
      • Developer Tools
      • GitOps
    • Secure Development & Architectures

      • Security
      • Secure coding
    • Platform Engineering

      • DevOps
      • DevSecOps
      • Ansible automation for applications and services
    • Automated Data Processing

      • AI/ML
      • Data Science
      • Apache Kafka on Kubernetes
      • View All Technologies
    • Start exploring in the Developer Sandbox for free

      sandbox graphic
      Try Red Hat's products and technologies without setup or configuration.
    • Try at no cost
  • Learn

    Featured

    • Kubernetes & Cloud Native
      Openshift icon
    • Linux
      Rhel icon
    • Automation
      Ansible cloud icon
    • Java
      Java icon
    • AI/ML
      AI/ML Icon
    • View All Learning Resources

    E-Books

    • GitOps Cookbook
    • Podman in Action
    • Kubernetes Operators
    • The Path to GitOps
    • View All E-books

    Cheat Sheets

    • Linux Commands
    • Bash Commands
    • Git
    • systemd Commands
    • View All Cheat Sheets

    Documentation

    • API Catalog
    • Product Documentation
    • Legacy Documentation
    • Red Hat Learning

      Learning image
      Boost your technical skills to expert-level with the help of interactive lessons offered by various Red Hat Learning programs.
    • Explore Red Hat Learning
  • Developer Sandbox

    Developer Sandbox

    • Access Red Hat’s products and technologies without setup or configuration, and start developing quicker than ever before with our new, no-cost sandbox environments.
    • Explore Developer Sandbox

    Featured Developer Sandbox activities

    • Get started with your Developer Sandbox
    • OpenShift virtualization and application modernization using the Developer Sandbox
    • Explore all Developer Sandbox activities

    Ready to start developing apps?

    • Try at no cost
  • Blog
  • Events
  • Videos

Report from the February 2023 ISO C++ meeting (Library)

October 5, 2023
Jonathan Wakely
Related products:
Red Hat Enterprise Linux

Share:

    The C++ standards committee (ISO/IEC JTC1/SC22/WG21, or WG21 to its friends) met in February to approve the final set of changes to the upcoming C++23 standard. The meeting was in Issaquah, in Washington, USA, and was the second time the committee had met in person since the pandemic. Like the meeting last November, this was a "hybrid" meeting, with in-person attendance but a large number of people (including me) attending virtually via video conference.

    Now that the contents of the C++23 are finished, we're waiting for the new standard to be published sometime later this year. The committee has successfully delivered a new revision of the C++ standard on time every three years since 2011, but this one has some special significance for me because I've been chairing WG21's Library Working Group (LWG) since we finished C++20 three years ago. I'm proud to have been able to help coordinate some of the great work that has gone into the new C++ standard, especially when we suddenly had to stop holding our regular meetings in 2020 and adopt new working practices.

    There are lots of new features in the C++23 standard library, but in this post, I will show a few examples of ones I think are particularly interesting. You might notice a theme: many of the new features are building on new features of C++20. Several of the features described below are smoothing away rough edges or filling in missing pieces of the features added to C++20.

    New feature highlights

    Building on the modules support added to C++20, there is now a std module for the standard library. This allows the entire standard library to be imported by using 'import std;' -- this not only means you don't need to remember which header files to include for each component you use but importing the entire library should compile much faster than including and preprocessing individual headers.

    Working with ranges

    Building on the <ranges> library introduced in C++20, there are many other new views and new algorithms for working with ranges; for example, views::zip and views::enumerate. The zip view of those takes any number of separate views and combines them into a single view yielding elements of type tuple<T&...>, i.e., a tuple of references to the elements of the individual views. The enumerate view takes a range of elements and produces a view that yields elements of type tuple<integer-type, T> such that each element of type T from the input range is paired with its index in the range. There are several more new views that yield different permutations of ranges, such as zip_transform, adjacent, adjacent_transform, join_with, chunk, chunk_by, slide, and cartesian_product.

    New <print> header

    Building on the <format> library introduced in C++20, the new <print> header provides convenient and type-safe printing to files and iostreams. In C++20 the classic "Hello, world!" program could be written in C++ as std::cout << std::format("Hello, {}!\n", "world"); . But with C++23, you can simply write std::println("Hello, {}!", "world"), which will both format the string and write it to standard output. The std::format and std::print functions also support more types than in C++20, including ranges (such as std::map, std::vector, and views such as the result of views::zip) and thread IDs and stack traces (which are another new addition in C++23).

    Error handling

    We also added discriminated union type, std::expected<T, U>, which holds either a result value or an error value. This allows a systematic approach to error handling that combines the best aspects of error codes and exceptions. You can think of an expected<T, U> object as being similar to optional<T> except instead of being empty when the expected T value, it contains an "unexpected" value of type U. This can be an error code (like the value of errno), an std::error_code, or anything representing the error that meant a T result could not be produced.

    Here is a quick demo showing some of these new features:

    import std;
    
    std::expected<std::vector<int>, std::error_code> get_data();
    
    int main()
    {
      try
      {
        auto indexed_vals = get_data().value() | std::views::enumerate;
        std::println("{}", indexed_vals);
      }
      catch (const std::bad_expected_access<std::error_code>& e)
      {
        std::println(std::cerr, "Failed to get data: {}: {}",
                     e.error().category().name(),
                     e.error().message());
      }
    }

    This will either print the vector with the index of each value, like "[(0, v0), (1, v1), (2, v2), ...]" or, if the get_data() function failed to produce a vector, calling the value() member function will throw an exception and then an error will be printed.

     

    Last updated: October 9, 2023
    Disclaimer: Please note the content in this blog post has not been thoroughly reviewed by the Red Hat Developer editorial team. Any opinions expressed in this post are the author's own and do not necessarily reflect the policies or positions of Red Hat.

    Related Posts

  • Report from the virtual ISO C++ meetings in 2020 (core language)

  • C++ standardization (core language) progress in 2021

  • Report from the February 2019 ISO C++ meeting (Library)

  • Migrating C and C++ applications from Red Hat Enterprise Linux version 7 to version 8

  • The joys and perils of aliasing in C and C++, Part 2

  • Recent Posts

    • How to deploy EVPN in OpenStack Services on OpenShift

    • Ollama or vLLM? How to choose the right LLM serving tool for your use case

    • How to build a Model-as-a-Service platform

    • How Quarkus works with OpenTelemetry on OpenShift

    • Our top 10 articles of 2025 (so far)

    Red Hat Developers logo LinkedIn YouTube Twitter Facebook

    Products

    • Red Hat Enterprise Linux
    • Red Hat OpenShift
    • Red Hat Ansible Automation Platform

    Build

    • Developer Sandbox
    • Developer Tools
    • Interactive Tutorials
    • API Catalog

    Quicklinks

    • Learning Resources
    • E-books
    • Cheat Sheets
    • Blog
    • Events
    • Newsletter

    Communicate

    • About us
    • Contact sales
    • Find a partner
    • Report a website issue
    • Site Status Dashboard
    • Report a security problem

    RED HAT DEVELOPER

    Build here. Go anywhere.

    We serve the builders. The problem solvers who create careers with code.

    Join us if you’re a developer, software engineer, web designer, front-end designer, UX designer, computer scientist, architect, tester, product manager, project manager or team lead.

    Sign me up

    Red Hat legal and privacy links

    • About Red Hat
    • Jobs
    • Events
    • Locations
    • Contact Red Hat
    • Red Hat Blog
    • Inclusion at Red Hat
    • Cool Stuff Store
    • Red Hat Summit
    © 2025 Red Hat

    Red Hat legal and privacy links

    • Privacy statement
    • Terms of use
    • All policies and guidelines
    • Digital accessibility

    Report a website issue