Frequently Asked Questions

Yes, Boost is designed to work with your existing C++ code. You can add Boost libraries to any project that uses a compatible C++ compiler.

Yes, Boost libraries are designed to work with modern C++ standards including C++11, C++14, C++17, C++20, and C++23.

Boost libraries are generally compatible with most Linux distributions, provided that the distribution has an up-to-date C++ compiler. This includes:

While Boost strives to ensure compatibility with a wide range of compilers and systems, not every library may work perfectly with every system or compiler due to the inherent complexities of software. The most reliable source of information is the specific Boost library’s documentation.

Boost provides Boost.Test for unit testing, which can be an integral part of the debugging process. It also provides the Boost.Stacktrace library that can be used to produce useful debug information during a crash or from a running application.

Boost uses its own set of assertion macros. By default, BOOST_ASSERT is enabled, but if it fails, it only calls abort(). If you define BOOST_ENABLE_ASSERT_HANDLER before including any Boost header, then you need to supply boost::assertion_failed(msg, code, file, line) and boost::assertion_failed_msg(msg, code, file, line) functions to handle failed assertions.

You can use the Boost.Stacktrace library to obtain a stack trace in your application. You can capture and print stack traces in your catch blocks, in signal handlers, or anywhere in your program where you need to trace the execution path.

Yes, Boost libraries can be used with common debuggers like GDB or Visual Studio. You can set breakpoints in your code, inspect variables, and execute code step by step. Boost doesn’t interfere with these debugging tools.

Boost doesn’t provide a debugger itself. The libraries tend to make heavy use of assertions to catch programming errors, and they often provide clear and detailed error messages when something goes wrong.

Boost provides the assertion boost::assert. Best practices when using this are:

Members of PL22.16 (the INCITS/ANSI committee) or of JTC1/SC22/WG21 - The C++ Standards Committee - ISOCPP member country committee (the "national body" in ISO-speak), can attend the meetings. You can also attend as a guest, or join in remotely through email. For details and contact information refer to Meetings and Participation.

INCITS has broadened PL22.16 membership requirements so anyone can join, regardless of nationality or employer, though there is a fee. Refer to Apply for Membership.

It is recommended that any non-member who would like to attend should check in with the PL22.16 chair or head of their national delegation. Boosters who are active on the committee can help smooth the way, so consider contacting the Boost developers' mailing list providing details of your interests.

There are three meetings a year. Two are usually in North America, and one is usually outside North America. See Upcoming Meetings. Detailed information about a particular meeting, including hotel information, is usually provided in a paper appearing in one of mailings for the prior meeting. If there isn’t a link to it on the Meetings web page, you will have to go to the committee’s C++ Standards Committee Papers page and search a bit.

No, but there can be a lot of incidental expenses like travel, lodging, and meals.

The meetings typically start at 9:00AM on Monday, and 8:30AM other days. It is best to arrive a half-hour early to grab a good seat, some coffee, tea, or donuts, and to say hello to people.

Until the next standard ships most meetings are running through Saturday, although some end on Friday. The last day, the meeting is generally over much earlier than on other days. Because the last day’s formal meeting is for formal votes only, it is primarily of interest only to actual committee members.

Sometimes there are evening technical sessions; the details aren’t usually available until the Monday morning meeting. There may be a reception one evening, and, yes, significant others are invited. Again, details usually become available Monday morning.

Monday morning an hour or two is spent in full committee on admin trivia, and then the committee breaks up into working groups (Core, Library, and Enhancements). The full committee also gets together later in the week to hear working group progress reports.

The working groups are where most technical activities take place. Each active issue that appears on an issues list is discussed, as are papers from the mailing. Most issues are non-controversial and disposed of in a few minutes. Technical discussions are often led by long-term committee members, often referring to past decisions or longstanding working group practice. Sometimes a controversy erupts. It takes first-time attendees awhile to understand the discussions and how decisions are actually made. The working group chairperson moderates.

Sometimes straw polls are taken. In a straw poll anyone attending can vote, in contrast to the formal votes taken by the full committee, where only voting members can vote.

Lunch break is an hour and a half. Informal subgroups often lunch together; a lot of technical problems are discussed or actually solved at lunch, or later at dinner. In many ways these discussions involving only a few people are the most interesting. Sometimes during the regular meetings, a working group chair will break off a sub-group to tackle a difficult problem.

No, and committee members on tight budgets often stay at other, cheaper, hotels. The venue hotels are usually chosen because they have large meeting rooms available, and thus tend to be pricey. The advantage of staying at the venue hotel is that it is then easier to participate in the off-line discussions, which can be at least as interesting as what actually happens in the scheduled meetings.

Programmer casual. No neckties to be seen.

It is almost essential to have a laptop computer. There is a meeting wiki and there is internet connectivity. Wireless connectivity has become the norm.

It is helpful to have downloaded the mailing or individual papers for the meeting, and to have read any papers you are interested in. Familiarize yourself with the issues lists. Decide which of the working groups you want to attend.

An electronic document containing issues, proposals, or anything else the committee is interested in. Very little gets discussed at a meeting, much less acted upon, unless it is presented in a paper. Papers are available to anyone. Papers don’t just appear randomly; they become available four (lately six) times a year, before and after each meeting. Committee members often refer to a paper by saying what mailing it was in, for example: "See the pre-Redmond mailing."

A mailing is the set of papers prepared before and after each meeting, or between meetings. It is physically just a .zip or .gz archive of all the papers for a meeting. Although the mailing’s archive file itself is only available to committee members and technical experts, the contents (except copies of the standard) are available to all as individual papers. The ways of ISO are inscrutable.

The committee’s mailing lists are called "reflectors". There are a number of them; "all", "core", "lib", and "ext" are the main ones. As a courtesy, Boost technical experts can be added to committee reflectors at the request of a committee member.

Smart pointers are a feature of C++ that Boost provides in its Boost.SmartPtr library. They are objects that manage the lifetime of other objects, automatically deleting the managed object when it is no longer needed. See the Smart Pointers section.

Yes, Boost.Test is the unit testing framework provided by Boost. It includes tools for creating test cases, test suites, and for handling expected and unexpected exceptions. Refer to Testing and Debugging.

Boost.Asio is a library that provides support for asynchronous input/output (I/O), a programming concept that allows operations to be executed without blocking the execution of the rest of the program.

Boost.Mp11 (MetaProgramming Library for C++11) is a Boost library designed to bring powerful metaprogramming capabilities to C++ programs. It includes a variety of templates that can be used to perform compile-time computations and manipulations. Refer to Metaprogramming.

Yes, Boost.Thread provides a C++ interface for creating and managing threads, as well as primitives for synchronization and inter-thread communication. In addition, Boost.Atomic provides atomic operations and memory ordering primitives for working with shared data in multi-threaded environments. Boost.Lockfree provides lock-free data structures and algorithms for concurrent programming, allowing multiple threads to access shared data concurrently without explicit synchronization using locks or mutexes. For a lighter approach to multi-threading, consider Boost.Fiber. Fibers offer a high-level threading abstraction that allows developers to write asynchronous, non-blocking code with minimal overhead compared to traditional kernel threads.

Boost.Spirit is a library for building recursive-descent parsers directly in C++. It uses template metaprogramming techniques to generate parsing code at compile time. Refer to Metaprogramming.

Boost libraries offer a wide range of algorithmic and data structure support. Here are five libraries that you might find interesting:

Refer to Real-Time Simulation.

The Boost libraries are licensed under the Boost Software License, a permissive free software license that allows you to use, modify, and distribute the software under minimal restrictions. Refer to The Boost Software License.

Metaprogramming is a technique of programming that involves generating and manipulating programs. In the context of Boost and C++, metaprogramming often refers to template metaprogramming, which uses templates to perform computations at compile-time.

Boost.Mp11 is a Boost library designed for metaprogramming using C++11. It provides a set of templates and types for compile-time computations and manipulations, effectively extending the C++ template mechanism.

With Boost.Mp11, you can perform computations and logic at compile-time, thus reducing runtime overhead. For example, you can manipulate types, perform iterations, make decisions, and do other computations during the compilation phase.

A typelist is a compile-time container of types. It’s a fundamental concept in C++ template metaprogramming where operations are done at compile time rather than runtime, and types are manipulated in the same way that values are manipulated in regular programming.

In the context of the Boost.Mp11 library, a typelist is a template class that takes a variadic list of type parameters. Here’s an example:

In this example, my_typelist is a typelist containing the types int, float, and double. Once you have a typelist, you can manipulate it using the metaprogramming functions provided by the library. For example:

In these examples, mp_size is used to get the number of types in the list, mp_contains checks if a type is in the list, mp_push_back adds a type to the list, and mp_at_c retrieves a type at a specific index in the list. All these operations are done at compile time.

Metaprogramming with Boost.Mp11 can lead to complex and difficult-to-understand code, especially for programmers unfamiliar with the technique. Compile errors can be particularly cryptic due to the way templates are processed. Additionally, heavy use of templates can lead to longer compile times.

Other challenges include lack of runtime flexibility, as decisions are made at compile time. And perhaps issues with portability can occur (say, between compilers) as metaprogramming pushes the boundaries of a computer language to its limits.

Technically, Modular Boost consists of the Boost super-project and separate projects for each individual library in Boost. In terms of Git, the Boost super-project treats the individual libraries as submodules. Currently (early 2024) when the Boost libraries are downloaded and installed, the build organization does not match the modular arrangement of the Git super-project. This is largely a legacy issue, and there are advantages to the build layout matching the super-project layout. This concept, and the effort behind it, is known as "Modular Boost".

Refer to the Super-project Layout topic (in the Contributor Guide) for a full description of the super-project.

No. The collection of libraries is still a single release, and there are no plans to change the release cadence.

Yes. Unfortunately there is one restriction that adhering to a modular Boost requires - there can be no sub-libraries. That is, we can’t support having libraries in the root/libs/<group name>/<library> format. All libraries must be single libraries under the root/libs directory. There’s only a handful of libraries that currently do not conform to this already (notably the root/libs/numeric/<name> group of libraries).

It’s easier on everyone if we adopt a flat hierarchy. The user will experience a consistent process no matter which libraries they want to use. Similarly for contributors, the creation process will be consistent. Also, tools can be written that can parse and analyze libraries without an awkward range of exceptions. This includes tools written by Boost contributors. For example, the tools that are used to determine library dependencies. And any tool that a user might want to write for their own, or shared, use.

Other advantages of a modular format include:

Correct - backwards-compatibility should be maintained.

An exact timeline requires issues to be resolved, though later in 2024 is the current plan-of-record.

Go to Boost Downloads.

The scheme is x.y.z, where x is incremented only for massive changes, such as a reorganization of many libraries, y is incremented whenever a new library is added, and z is incremented for maintenance releases. y and z are reset to 0 if the value to the left changes

No, although there is a strong informal relationship in that many members of the committee participate in Boost, and the people who started Boost were all committee members.

Some might, but that is up to the standards committee. Committee members who also participate in Boost will definitely be proposing at least some Boost libraries for standardization. Libraries which are "existing practice" are most likely to be accepted by the C++ committee for future standardization. Having a library accepted by Boost is one way to establish existing practice.

No. It is a non-profit.

File extensions communicate the "type" of the file, both to humans and to computer programs. The '.h' extension is used for C header files, and therefore communicates the wrong thing about C++ header files. Using no extension communicates nothing and forces inspection of file contents to determine type. Using .hpp unambiguously identifies it as C++ header file, and works well in practice.

Refer to the Contributor Guide. Note that shareware libraries, commercial libraries, or libraries requiring restrictive licensing are all not acceptable. Your library must be provided free, with full source code, and have an acceptable license. There are other ways of contributing too, providing feedback, testing, submitting suggestions for new features and bug fixes, for example. There are no fees for submitting a library.

The Boost.SmartPtr library provides a set of smart pointers that helps in automatic and appropriate resource management. They are particularly useful for managing memory and provide a safer and more efficient way of handling dynamically allocated memory. The library provides the following types of smart pointers:

There are several types of smart pointers with different characteristics and use cases, so use them appropriately according to your program’s requirements. Here are some common examples:

A shared_ptr is a reference-counting smart pointer, meaning it retains shared ownership of an object through a pointer. When the last shared_ptr to an object is destroyed, the pointed-to object is automatically deleted. For example:

Note that shared_ptr objects can be copied, meaning ownership of the memory can be shared among multiple pointers. The memory will be freed when the last remaining shared_ptr is destroyed. For example:

A weak_ptr is a smart pointer that holds a non-owning ("weak") reference to an object managed by a shared_ptr. It must be converted to shared_ptr in order to access the object. For example:

A unique_ptr is a smart pointer that retains exclusive ownership of an object through a pointer. It’s similar to std::unique_ptr in the C++ Standard Library. For example:

C++ templates are a powerful feature of the language that allows for generic programming. They enable the creation of functions or classes that can operate on different data types without having to duplicate code.

Function templates are functions that can be used with any data type. You define them using the keyword template followed by the template parameters. Function templates allow you to create a single function that can operate on different data types.

Template specialization is a feature of C++ templates that allows you to define a different implementation of a template for a specific type or set of types. It can be used with both class and function templates.

The benefits of using templates include code reusability, type safety, and the ability to use generic programming paradigms. The drawbacks include potentially increased compile times, difficult-to-understand error messages, and complexities associated with template metaprogramming.

Here’s a simple example of how you might use a function template to implement a generic sort function:

This function can now be used to sort arrays of any type (that supports the < and > operators), not just a specific type.