more/getting_started.rst

Getting Started With Boost __

This guide will help you get started using the Boost libraries. Have fun!

Index

Getting Boost

There are basically three ways to get Boost on your system:

1. Download and run the Windows installer supplied by Boost Consulting (not available for Boost alpha/beta releases).

2. or, download a complete Boost distribution from SourceForge.

Windows users

boost_1_34_0.exe is a program you can run to unpack the distribution; if you prefer not to download executable programs, get boost_1_34_0.zip and use an external tool to decompress it. We don't recommend using Windows' built-in decompression as it can be painfully slow for large archives.

*nix users

Download boost_1_34_0.tar.bz2, then, in the directory where you want to put the Boost installation, execute

tar --bzip2 -xf /path/to/boost_1_34_0.tar.bz2

3. or use a Boost package from RedHat, Debian, or some other distribution packager. These instructions may not work for you if you use this method, because other packagers sometimes choose to break Boost up into several packages or to reorganize the directory structure of the Boost distribution.¹

The Structure of a Boost Distribution

This is is a sketch of the directory structure you'll get when you unpack your Boost installation (windows users replace forward slashes with backslashes):

boost_1_34_0/ .................The “boost root directory”

index.html ....................A copy of www.boost.org boost/ .........................All Boost Header files libs/ ............Tests, .cpps, docs, etc., by library² index.html ........Library documentation starts here algorithm/ any/ array/ …more libraries… status/ .........................Boost-wide test suite tools/ ...........Utilities, e.g. bjam, quickbook, bcp more/ ..........................Policy documents, etc. doc/ ...............A subset of all Boost library docs

Header Organization

The organization of Boost library headers isn't entirely uniform, but most libraries follow a few patterns:

• Some older libraries and most very small libraries place all public headers directly into boost/.
• Most libraries' public headers live in a subdirectory of boost/ named after the library. For example, you'll find the Type Traits Library's is_void.hpp header in boost/type_traits/is_void.hpp.
• Some libraries have an “aggregate header” in boost/ that #includes all of the library's other headers. For example, Boost.Python's aggregate header is boost/python.hpp.
• Most libraries place private headers in a subdirectory called detail/ or aux_/. Don't look in these directories and expect to find anything you can use.

A few things are worth noting right off the bat:

1. The path to the “boost root directory” is sometimes referred to as $BOOST_ROOT in documentation and mailing lists. If you used the Windows installer, that will usually be C:\Program Files\boost\boost_1_34_0.

2. To compile anything in Boost, you need a directory containing the boost/ subdirectory in your #include path. For most compilers, that means adding

   -I/path/to/boost_1_34_0

   to the command line. Specific steps for setting up #include paths in Microsoft Visual Studio follow later in this document; if you use another IDE, please consult your product's documentation for instructions.

3. Since all of Boost's header files have the .hpp extension, and live in the boost/ subdirectory of the boost root, your Boost #include directives will look like:

   #include <boost/whatever.hpp>

   or

   #include "boost/whatever.hpp"

depending on your religion as regards the use of angle bracket includes. Even Windows users can use forward slashes in #include directives; your compiler doesn't care.

4. Don't be distracted by the doc/ subdirectory; it only contains a subset of the Boost documentation. Start with libs/index.html if you're looking for the whole enchilada.

Building a Simple Boost Program

The first thing many people want to know is, “how do I build Boost?” The good news is that often, there's nothing to build.

Header-Only Libraries

Nearly all Boost libraries are header-only. That is, most consist entirely of header files containing templates and inline functions, and require no separately-compiled library binaries or special treatment when linking.

The only Boost libraries that are not header-only are:

• Boost.Filesystem
• Boost.IOStreams
• Boost.ProgramOptions
• Boost.Python
• Boost.Regex
• Boost.Serialization
• Boost.Signals
• Boost.Test
• Boost.Thread
• Boost.Wave

The DateTime library has a separately-compiled binary which is only needed if you're using a “legacy compiler”(such as?). The Graph library has a separately-compiled binary, but you won't need it unless you intend to parse GraphViz files.

The following program reads a sequence of integers from standard input, uses Boost.Lambda (a header-only library) to multiply each one by three, and writes them to standard output:

#include <boost/lambda/lambda.hpp>
#include <iostream>
#include <iterator>
#include <algorithm>

int main() 
{
    using namespace boost::lambda;
    typedef std::istream_iterator<int> in;

    std::for_each( 
        in(std::cin), in(), std::cout << (_1 * 3) << " " );
}

Start by copying the text of this program into a file called example.cpp.

*nix (e.g. Unix, Linux, MacOS, Cygwin)

Simply issue the following command ($ represents the prompt issued by the shell, so don't type that):

$ c++ -I /path/to/boost_1_34_0 example.cpp -o example

To test the result, type:

$ echo 1 2 3 | ./example

Microsoft Windows Command-Line using Visual C++

From your computer's Start menu, select if you are a Visual Studio 2005 user, select

All Programs > Microsoft Visual Studio 2005 > Visual Studio Tools > Visual Studio 2005 Command Prompt

or if you're a Visual Studio .NET 2003 user, select

All Programs > Microsoft Visual Studio .NET 2003 > Visual Studio .NET Tools > Visual Studio .NET 2003 Command Prompt

to bring up a special command prompt window set up for the Visual Studio compiler. In that window, type the following command and hit the return key (C:\PROMPT> represents the prompt issued by the shell, so don't type that):

C:PROMPT> cl /EHsc /I C:\path\to\boost_1_34_0 example.cpp

To test the result, type:

C:PROMPT> echo 1 2 3 | example

Visual Studio .NET 2003 or Visual Studio 2005

• From Visual Studio's File menu, select New > Project…
• In the left-hand pane of the resulting New Project dialog, select Visual C++ > Win32.
• In the right-hand pane, select Win32 Console Application (VS8.0) or Win32 Console Project (VS7.1).
• In the name field, enter “example”
• Right-click example in the Solution Explorer pane and select Properties from the resulting pop-up menu
• In Configuration Properties > C/C++ > General > Additional Include Directories, enter the path to the Boost root directory, e.g. C:\Program Files\boost\boost_1_34_0.
• In Configuration Properties > C/C++ > Precompiled Headers, change Use Precompiled Header (/Yu) to Not Using Precompiled Headers.³
• Replace the contents of the example.cpp generated by the IDE with the example code above.
• From the Build menu, select Build Solution.

To test your application, hit the F5 key and type the following into the resulting window, followed by the return key:

1 2 3

Then hold down the control key and press "Z", followed by the return key.

Other Compilers/Environments

Consult your vendor's documentation; if you have trouble adapting these instructions to your build environment, request assistance on the Boost Users' mailing list.

Getting Boost Library Binaries

If you want to use any of the separately-compiled Boost libraries, you'll need to get ahold of library binaries.

Microsoft Visual C++ 8.0 or 7.1 (Visual Studio 2005/.NET 2003) Binaries

The Windows installer supplied by Boost Consulting will download and install pre-compiled binaries into the lib\ subdirectory of the boost root, typically C:\Program Files\boost\boost_1_34_0\lib\.

*nix (e.g. Unix, Linux, MacOS, Cygwin) Binaries

Issue the following commands in the shell (again, $ represents the shell's prompt):

$ cd /path/to/boost_1_34_0 $ ./configure --help

Select your configuration options and invoke ./configure again. Unless you have write permission in your system's /usr/local/ directory, you'll probably want to at least use

$ ./configure --prefix=path/to/installation/prefix

to install somewhere else. Finally,

$ make install

which will leave Boost binaries in the lib/ subdirectory of your installation prefix. You will also find a copy of the Boost headers in the include/ subdirectory of the installation prefix, so you can henceforth use that directory as an #include path in place of the Boost root directory.

Other Compilers/Environments

If you're not using Visual C++ 7.1 or 8.0, or you're a *nix user who wants want to build with a toolset other than your system's default, or if you want a nonstandard variant build of Boost (e.g. optimized, but with debug symbols), you'll need to use Boost.Build to create your own binaries.

Building Boost Binaries with Boost.Build

Like an IDE, Boost.Build is a system for developing, testing, and installing software. Instead of using a GUI, though, Boost.Build is text-based, like make. Boost.Build is written in the interpreted Boost.Jam language.

To use Boost.Build, you'll need an executable called bjam, the Boost.Jam interpreter.

When you use Boost.Build to build your own project, you don't need a separate step to create Boost binaries: you simply refer to the boost library targets from your Jamfile and the are built automatically (refer to the Boost.Build documentation for detailed instructions). Here, we're assuming you're using a different build system for your own code, so you need to explicitly generate Boost binaries. We're also assuming that you have a complete Boost distribution somewhere.

Getting bjam

Using command-line tools in Windows

In Windows, a command-line tool is invoked by typing its name, optionally followed by arguments, into a Command Prompt window and pressing the Return (or Enter) key.

To open Command Prompt, click the Start menu button, click Run, type “cmd”, and then click OK.

All commands are executed within the context of a current directory in the filesystem. To set the current directory, type:

cd path\to\some\directory

followed by Return. For example,

cd C:\Program Files\boost\boost_1_34_0

One way to name a directory you know about is to write

%HOMEDRIVE%%HOMEPATH%\directory-name

which indicates a sibling folder of your “My Documents” folder.

Long commands can be continued across several lines by typing backslashes at the ends of all but the last line. Many of the examples on this page use that technique to save horizontal space.

Boost provides pre-compiled bjam executables_ for a variety of platforms. Alternatively, you can build bjam yourself using the instructions given in the Boost.Jam documentation.

bjam is a command-line tool. To build Boost binaries, you'll invoke bjam with the current directory set to the Boost root, and with options described in the following sections.

Identify Your Toolset

First, find the toolset corresponding to your compiler in the following table.

Toolset Name	Vendor	Notes
acc	Hewlett Packard	Only very recent versions are known to work well with Boost
borland	Borland
como	Comeau Computing	Using this toolset may require configuring another toolset to act as its backend
cw	Metrowerks/FreeScale	The CodeWarrior compiler. We have not tested versions of this compiler produced since it was sold to FreeScale.
dmc	Digital Mars	As of this Boost release, no version of dmc is known to handle Boost well.
gcc	The Gnu Project
hp_cxx	Hewlett Packard	Targeted at the Tru64 operating system.
intel	Intel
kylix	Borland
msvc	Microsoft
qcc	QNX Software Systems
sun	Sun
vacpp	IBM	The VisualAge C++ compiler.

If you have multiple versions of a particular compiler installed, you can apend the version number to the toolset name, preceded by a hyphen, e.g. msvc-7.1 or gcc-3.4.

Note

if you built bjam yourself, you may have selected a toolset name for that purpose, but that does not affect this step in any way; you still need to select a Boost.Build toolset from the table.

Select a Build Directory

Boost.Build will place all intermediate files it generates while building into the build directory. If your Boost root directory is writable, this step isn't strictly necessary: by default Boost.Build will create a bin.v2/ subdirectory for that purpose in your current working directory.

Invoke bjam

Change your current directory to the Boost root directory and invoke bjam as follows:

bjam --build-dir=build-directory_ \

--toolset=toolset-name_ stage

For example, on Windows, your session might look like:

C:WINDOWS> cd C:\Program Files\boost\boost_1_34_0 C:\Program Files\boost\boost_1_34_0> bjam \ --build-dir=%HOMEDRIVE%%HOMEPATH%\build-boost \ --toolset=msvc stage

Note

bjam is case-sensitive; it is important that all the parts shown in bold type above be entirely lower-case.

And on Unix:

~$ cd ~/boost_1_34_0 ~/boost_1_34_0$ bjam --build-dir=~/build-boost --prefix=~/boost

In either case, Boost.Build will place the Boost binaries in the stage/ subdirectory of your build directory.

stage

You already have the Boost headers on your system (in the boost/ subdirectory of your Boost distribution), so if you prefer not to create an additional copy, instead of installing Boost you can simply “stage” the Boost binaries, which leaves them in the stage/ subdirectory of your chosen build directory:

bjam --build-dir=build-directory_ \

--toolset=toolset-name_ stage

Select a Prefix Directory

Choose a prefix directory. The installation process will leave you with the following subdirectories of the prefix directory:

• lib, containing the Boost binaries
• include/boost_1_34_0, containing the Boost headers.

Change your current directory to the Boost root directory and invoke bjam as follows:

bjam --build-dir=build-directory_ \

--toolset=toolset-name_ \

--prefix=prefix-directory_ install

For example, on Windows your session might look like:

C:WINDOWS> cd C:\Program Files\boost\boost_1_34_0 C:\Program Files\boost\boost_1_34_0> bjam \ --build-dir=C:\TEMP\build-boost \ --prefix=C:\boost

And on Unix:

~$ cd ~/boost_1_34_0 ~/boost_1_34_0$ bjam --build-dir=/tmp/build-boost \ --prefix=~/boost

Linking A Program with a Boost Library

To demonstrate linking with a Boost binary library, we'll use the following simple program that extracts the subject lines from emails. It uses the Boost.Regex library, which has a separately-compiled binary component. :

#include <boost/regex.hpp>
#include <iostream>
#include <string>

int main()
{
    std::string line;
    boost::regex pat( "^Subject: (Re: |Aw: )*(.*)" );

    while (std::cin)
    {
        std::getline(std::cin, line);
        boost::smatch matches;
        if (boost::regex_match(line, matches, pat))
            std::cout << matches[2];
    }
}

There are two main challenges associated with linking:

1. Tool configuration, e.g. choosing command-line options or IDE build settings.
2. Identifying the library binary, among all the build variants, whose compile configuration is compatible with the rest of your project.

Microsoft Windows

Most Windows compilers and linkers have so called “auto-linking support,” which is used by many Boost libraries to eliminate the second challenge. Special code in Boost header files detects your compiler options and uses that information to encode the name of the correct library into your object files; the linker selects the library with that name from the directories you've told it to search.

Note

As of this writing, a few Boost libraries don't support auto-linking:

• Boost.Python
• …others?…

Visual C++ Command Line

For example, we can compile and link the above program from the Visual C++ command-line by simply adding the bold text below to the command line we used earlier, assuming your Boost binaries are in C:\Program Files\boost\boost_1_34_0\lib:

C:PROMPT> cl /EHsc /I C:\path\to\boost_1_34_0 example.cpp \

/link /LIBPATH: C:\Program Files\boost\boost_1_34_0\lib

To link with a library that doesn't use auto-linking support, you need to specify the library name. For example,

C:PROMPT> cl /EHsc /I C:\path\to\boost_1_34_0 example.cpp \

/link /LIBPATH: C:\Program Files\boost\boost_1_34_0 \ boost_regex-msvc-7.1-mt-d-1_34.lib

See Library Naming for details about how to select the right library name.

Visual Studio IDE

Starting with the header-only example project we created earlier:

1. Right-click example in the Solution Explorer pane and select Properties from the resulting pop-up menu
2. In Configuration Properties > Linker > Additional Library Directories, enter the path to the Boost binaries, e.g. C:\Program Files\boost\boost_1_34_0\lib\.
3. From the Build menu, select Build Solution.

To link with a library that doesn't use auto-linking support, before building (step 3 above), you also need to specify the library name:

• In Configuration Properties > Linker > Input > Additional Dependencies, enter the name of the binary library to link with, e.g. boost_regex-msvc-7.1-mt-d-1_34.lib.

See Library Naming for details about how to select the right library name.

*nix (e.g. Unix, Linux, MacOS, Cygwin)

There are two main ways to link to libraries:

1. You can specify the full path to each library:

   $ c++ -I /path/to/boost_1_34_0 example.cpp -o example \

   ~/boost/lib/libboost_regex-msvc-7.1-mt-d-1_34.a

2. You can separately specify a directory to search (with -Ldirectory) and a library name to search for (with -llibrary,⁴ dropping the filename's leading lib and trailing suffix (.a in this case):

   $ c++ -I /path/to/boost_1_34_0 example.cpp -o example \

   -L~/boost/lib/ -lboost_regex-msvc-7.1-mt-d-1_34

   As you can see, this method is just as terse as method a. for one library; it really pays off when you're using multiple libraries from the same directory.

In both cases above, the bold text is what you'd add to the command lines we explored earlier.

Library Naming

In order to choose the right library binary to link with, you'll need to know something about how Boost libraries are named. Each library binary filename is composed of a common sequence of elements that describe how it was built. For example, libboost_regex-msvc-7.1-mt-d-1_34.lib can be broken down into the following elements:

lib

Prefix: except on Microsoft Windows, every Boost library name begins with this string. On Windows, only ordinary static libraries use the lib prefix; import libraries and DLLs do not.⁵

boost_regex

Library name: all boost library filenames begin with boost_.

-msvc-7.1

Toolset tag: one of the Boost.Build toolset names, possibly followed by a dash and a version number.

-mt

Threading tag: indicates that the library was built with multithreading support enabled. Libraries built without multithreading support can be identified by the absence of -mt.

-d

ABI tag: encodes details that affect the library's interoperability with other compiled code. For each such feature, a single letter is added to the tag:

Key	Use this library when:
s	linking statically to the C++ standard library and compiler runtime support libraries.
g	using debug versions of the standard and runtime support libraries.
y	using a special debug build of Python.
d	building a debug version of your code.6
p	using the STLPort standard library rather than the default one supplied with your compiler.
n	using STLPort's deprecated “native iostreams” feature.7

For example, if you build a debug version of your code for use with debug versions of the static runtime library and the STLPort standard library in “native iostreams” mode, the tag would be: -sgdpn. If none of the above apply, the ABI tag is ommitted.

-1_34

Version tag: the full Boost release number, with periods replaced by underscores. The major and minor version numbers are taken together separated by an underscore. For example, version 1.31.1 would be tagged as "-1_31_1".

.lib

Extension: determined according to the operating system's usual convention. On Windows, .dll indicates a shared library and .lib indicates a static or import library. On most *nix platforms the extensions are .a and .so for static libraries (archives) and shared libraries, respectively. Where supported by *nix toolsets, a full version extension is added (e.g. ".so.1.34"); a symbolic link to the library file, named without the trailing version number, will also be created.

---

---

1. If developers of Boost packages would like to work with us to make sure these instructions can be used with their packages, we'd be glad to help. Please make your interest known to the Boost developers' list.↩︎

2. If you used the Windows installer from Boost Consulting and deselected “Source and Documentation” (it's selected by default), you won't see the libs/ subdirectory. That won't affect your ability to use precompiled binaries, but you won't be able to rebuild libraries from scratch.↩︎

3. There's no problem using Boost with precompiled headers; these instructions merely avoid precompiled headers because it would require Visual Studio-specific changes to the source code used in the examples.↩︎

4. That option is a dash followed by a lowercase “L” character, which looks very much like a numeral 1 in some fonts.↩︎

5. This convention distinguishes the static version of a Boost library from the import library for an identically-configured Boost DLL, which would otherwise have the same name.↩︎

6. These libraries were compiled without optimization or inlining, with full debug symbols enabled, and without NDEBUG #defined. All though it's true that sometimes these choices don't affect binary compatibility with other compiled code, you can't count on that with Boost libraries.↩︎

7. This feature of STLPort is deprecated because it's impossible to make it work transparently to the user; we don't recommend it.↩︎