cmake的亮点在于编译复杂项目上的应用 —— cmake是一个跨平台的Makefile 生成工具! 一言以蔽之——cmake 为项目自动生成Makefile, 虽然cmake功能远不止步于此,但是本文聚焦于此。
源代码只有一个文件HelloWorld.cpp
#include
int main(int argc, char *argv[]){
std::cout << "Hello World!" << std::endl;
return 0;
}
CMakeLists.txt也只有三行而已(使用cmake管理项目的过程,也就是编写CMakeLists.txt的过程)
cmake_minimum_required(VERSION 2.8.9)
project (hello)
add_executable(hello helloworld.cpp)
第一行用于指定cmake最低版本
第二行指定项目名称(这个名称是任意的)
第三行指定编译一个可执行文件,hello是第一个参数,表示生成可执行文件的文件名(这个文件名也是任意的),第二个参数helloworld.cpp则用于指定源文件。
如果您电脑上已经安装了cmake,那么我们就已经完事具备了。
第一步,用cmake生成Makefile文件
在例1中完全体现不出cmake的任何优势,用g++一行可以解决的问题我们绕了一大圈。可是cmake本来的优势就是管理庞大的项目的。
这个例子用最小的程序来体现一个带目录结构的项目。其中有源文件目录,头文件目录。
cmake_minimum_required(VERSION 2.8.9)
project(directory_test)
#Bring the headers, such as Student.h into the project
include_directories(include)
#Can manually add the sources using the set command as follows:
#set(SOURCES src/mainapp.cpp src/Student.cpp)
#However, the file(GLOB...) allows for wildcard additions:
file(GLOB SOURCES "src/*.cpp")
add_executable(testStudent ${SOURCES})
和第一个例子比起来,CMakelist.txt有如下改变:
有了前两个例子的基础,接下来的例子我们只需要看一下目录结构和CMakelist.txt.
CMakelist.txt如下:
project(directory_test)
set(CMAKE_BUILD_TYPE Release)
#Bring the headers, such as Student.h into the project
include_directories(include)
#However, the file(GLOB...) allows for wildcard additions:
file(GLOB SOURCES "src/*.cpp")
#Generate the shared library from the sources
add_library(testStudent SHARED ${SOURCES})
#Set the location for library installation -- i.e., /usr/lib in this case
# not really necessary in this example. Use "sudo make install" to apply
install(TARGETS testStudent DESTINATION /usr/lib)
两个重要变化:
基于例3,我们编译一个静态库
将CMakeList.txt修改为如下所示:
cmake_minimum_required(VERSION 2.8.9)
project(directory_test)
set(CMAKE_BUILD_TYPE Release)
#Bring the headers, such as Student.h into the project
include_directories(include)
#However, the file(GLOB...) allows for wildcard additions:
file(GLOB SOURCES "src/*.cpp")
#Generate the static library from the sources
add_library(testStudent STATIC ${SOURCES})
#Set the location for library installation -- i.e., /usr/lib in this case
# not really necessary in this example. Use "sudo make install" to apply
install(TARGETS testStudent DESTINATION /usr/li
可以看出,只需将add_library中的shared改为static即可。
编译结果如下:
下边我们来测试一下我们例3的结果,代码和CMakeList.txt如下:
#include"Student.h"
int main(int argc, char *argv[]){
Student s("Joe");
s.display();
return 0;
}
cmake_minimum_required(VERSION 2.8.9)
project (TestLibrary)
#For the shared library:
set ( PROJECT_LINK_LIBS libtestStudent.so )
link_directories( ~/exploringBB/extras/cmake/studentlib_shared/build )
#For the static library:
#set ( PROJECT_LINK_LIBS libtestStudent.a )
#link_directories( ~/exploringBB/extras/cmake/studentlib_static/build )
include_directories(~/exploringBB/extras/cmake/studentlib_shared/include)
add_executable(libtest libtest.cpp)
target_link_libraries(libtest ${PROJECT_LINK_LIBS} )