boost::format使用

1. boost安装

1.1. yum安装

进入root帐户，运行以下三行命令即可

yum install boost
yum install boost-devel
yum install boost-doc

安装完毕后，可以在usr/include里面找到头文件，cmake配置好后一直没找到库文件，Boost_LIBRARIES的值一直为空，值为空的原因是我只是find_package(Boost)，没有指定组件，指定了还报错的话，个人猜测可能是上面几行命令还不够，因为yum list | grep boost后除了以上三个安装包外，还有很多库文件的包，如boost-filesystem.i686,虽然可以通过yum install boost*暴力安装，但也不清楚有没有缺东西，所以采用压缩包安装的方式。如果只是用一些包的话，也可以用yum把需要的包装上。

1.2. 压缩包安装

1.2.1. 官网下载boost

下载boost，下载完成后解压，并进入解压缩后的目录

tar --bzip2 -xf boost_1_57_0.tar.bz2
cd boost_1_57_0

建议下载tar.gz文件，bz2文件可能构建Jamfile，解压缩时注意解压完全

1.2.2. 编译安装boost

打开目录下的index.html网页，进入Getting_started，在右下角点击Getting started on Unix variants(e.g.Linux, MacOS) ，然后按照官方给的帮助进行安装。简单编译安装如下：

./bootstrap.sh --prefix=path/to/installation/prefix
./b2 install

如果安装后想马上使用boost库进行编译，还需要执行一下这个命令：

ldconfig

更新一下系统的动态链接库

2. Linux下cmake编译时链接boost库

2.1. find_package

find_package是CMake打包配置文件的工具。Find Boost包括目录和库
通过以下形式调用find_package来使用此模块：

find_package(Boost
  [version] [EXACT]      # Minimum or EXACT version e.g. 1.36.0
  [REQUIRED]             # Fail with error if Boost is not found
  [COMPONENTS <libs>...] # Boost libraries by their canonical name
  )                      # e.g. "date_time" for "libboost_date_time"

find_package必须小写，以下变量名注意大小写
在上述命令成功运行完后，可以得到保存路径等信息的变量，如

Boost_FOUND            - True if headers and requested libraries were found
Boost_INCLUDE_DIRS     - Boost include directories
Boost_LIBRARY_DIRS     - Link directories for Boost libraries
Boost_LIBRARIES        - Boost component libraries to be linked
Boost_<C>_FOUND        - True if component <C> was found (<C> is upper-case)
Boost_<C>_LIBRARY      - Libraries to link for component <C> (may include
                         target_link_libraries debug/optimized keywords)
Boost_VERSION          - BOOST_VERSION value from boost/version.hpp
Boost_LIB_VERSION      - Version string appended to library filenames
Boost_MAJOR_VERSION    - Boost major version number (X in X.y.z)
Boost_MINOR_VERSION    - Boost minor version number (Y in x.Y.z)
Boost_SUBMINOR_VERSION - Boost subminor version number (Z in x.y.Z)
Boost_LIB_DIAGNOSTIC_DEFINITIONS (Windows)
                       - Pass to add_definitions() to have diagnostic
                         information about Boost's automatic linking
                         displayed during compilation

在搜索package前，可以设置变量辅助搜索

BOOST_ROOT             - Preferred installation prefix
 (or BOOSTROOT)
BOOST_INCLUDEDIR       - Preferred include directory e.g. <prefix>/include
BOOST_LIBRARYDIR       - Preferred library directory e.g. <prefix>/lib
Boost_NO_SYSTEM_PATHS  - Set to ON to disable searching in locations not
                         specified by these hint variables. Default is OFF.
Boost_ADDITIONAL_VERSIONS
                       - List of Boost versions not known to this module
                         (Boost install locations may contain the version)

将搜索结果永久保存在CMake缓存条目中：

Boost_INCLUDE_DIR         - Directory containing Boost headers
Boost_LIBRARY_DIR         - Directory containing Boost libraries
Boost_<C>_LIBRARY_DEBUG   - Component <C> library debug variant
Boost_<C>_LIBRARY_RELEASE - Component <C> library release variant

仅查找Boost头文件的示例：

find_package(Boost 1.36.0)
if(Boost_FOUND)
  include_directories(${Boost_INCLUDE_DIRS})
  add_executable(foo foo.cc)
endif()

查找Boost头文件和一些静态库的示例：

set(Boost_USE_STATIC_LIBS        ON) # only find static libs
set(Boost_USE_MULTITHREADED      ON)
set(Boost_USE_STATIC_RUNTIME    OFF)
find_package(Boost 1.36.0 COMPONENTS date_time filesystem system ...)
if(Boost_FOUND)
  include_directories(${Boost_INCLUDE_DIRS})
  add_executable(foo foo.cc)
  target_link_libraries(foo ${Boost_LIBRARIES})
endif()

示例1：

cmake_minimum_required(VERSION 2.8)
PROJECT(WritePts)
SET(WritePtsSource 
       ./source/WritePts.cpp
)

set(BOOST_ROOT /usr/local)
find_package(Boost 1.57.0 COMPONENTS regex filesystem)
#find_package(Boost)

if(Boost_FOUND)
	INCLUDE_DIRECTORIES(${Boost_INCLUDE_DIRS})
	MESSAGE( STATUS "Boost_INCLUDE_DIRS = ${Boost_INCLUDE_DIRS}.")
	MESSAGE( STATUS "Boost_LIBRARIES = ${Boost_LIBRARIES}.")
	MESSAGE( STATUS "Boost_LIB_VERSION = ${Boost_LIB_VERSION}.")

	ADD_EXECUTABLE(WritePts ${WritePtsSource})
	TARGET_LINK_LIBRARIES(WritePts ${Boost_LIBRARIES})
endif()

注意文件中各个变量的大小写，如果这样设置后，还存在报错，第一步先核实一下各个变量名，如果没有问题，再根据报错信息确定可能出现的原因

示例2：

# CMakeLists.txt
project(tutorial-0)
cmake_minimum_required(VERSION 3.5)
set(CMAKE_CXX_STANDARD 14)

set(BOOST_ROOT /usr/local/install/boost_1_61_0)

find_package(Boost COMPONENTS regex system REQUIRED)

if(Boost_FOUND)
    include_directories(${Boost_INCLUDE_DIRS})
    
    MESSAGE( STATUS "Boost_INCLUDE_DIRS = ${Boost_INCLUDE_DIRS}.")
    MESSAGE( STATUS "Boost_LIBRARIES = ${Boost_LIBRARIES}.")
    MESSAGE( STATUS "Boost_LIB_VERSION = ${Boost_LIB_VERSION}.")

    add_executable(foo foo.cpp)
    target_link_libraries (foo ${Boost_LIBRARIES})
endif()

通过设置BOOST_ROOT来设置首选的搜索路径
通过MESSAGE函数把查找的结果都打印了出来

-- Boost_INCLUDE_DIRS = /usr/local/install/boost_1_61_0/include.
-- Boost_LIBRARIES = /usr/local/install/boost_1_61_0/lib/libboost_regex.so;/usr/local/install/boost_1_61_0/lib/libboost_system.so.
-- Boost_LIB_VERSION = 1_61.

编译过程需要用到的头文件搜索路径保存在变量Boost_INCLUDE_DIRS中，所需要link的库文件路径保存在变量Boost_LIBRARIES中

参考链接FindBoost

3. boost::format使用

安装好boost，配置好cmake之后，引入头文件format.cpp

#include <boost/format.hpp>