cmake 入门

构建hello项目

查看cmake 版本

$ cmake -version
cmake version 3.16.3

CMake suite maintained and supported by Kitware (kitware.com/cmake).

项目以及内容如下

文件目录

hello
├── CMakeLists.txt
├── hello.cpp
└── Makefile

hello.cpp

#include <iostream>
int main(int argc, char* argv[])
{
    std::cout << "hello cmake " << std::endl;
    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(hello)
add_executable(hello hello.cpp)

构建、编译与运行

$ cmake .
$ make
$ ./hello

• 生成以下文件：

  CMakeCache.txt  CMakeFiles  cmake_install.cmake  CMakeLists.txt  hello  hello.cpp  Makefile
  

• cmake 生成的文件以及最终的可执行文件 hello 与工程的源码文件 hello.cpp 混在了一起；并且清理 cmake 产生的文件时也变得麻烦；因此，需要将构建过程生成的文件与源文件分离，这就是 out-of-source build(内部构建和外部构建）。

清理后，再次构建、编译与运行（out-of-source）

$ mkdir build && cd build
$ cmake .. && make
$ ./hello

文件结构如下：
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ ├── hello
│ └── Makefile
├── CMakeLists.txt
├── hello.cpp
└── Makefile

还有一点不方便，就是可执行文件和cmake生成文件混在一起。

继续优化，修改cmake

cmake_minimum_required(VERSION 3.15)
project(hello)
set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/../bin)
add_executable(hello hello.cpp)

编译后，文件目录如下：
hello
├── CMakeCache.txt
├── CMakeFiles
├── cmake_install.cmake
├── hello
└── Makefile

清理后，继续构建、编译与运行

$ mkdir build && cd build && cmake .. && make && ./hello

编译后文件结构如下：
hello
├── bin
│ └── hello
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ └── Makefile
├── CMakeLists.txt
├── hello.cpp
└── Makefile

构建hello_v2项目

项目以及内容如下

文件目录

hello_v2
├── CMakeLists.txt
├── inc
│ └── hello.hpp
├── main.cpp
└── src
└── hello.cpp

main.cpp

#include <iostream>
#include "hello.hpp"

int main(int argc, char* argv[])
{
    hello();
    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.16)

project(hello_v2)

set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/../bin)

file(GLOB SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/src/*.cpp")

include_directories( $(CMAKE_CURRENT_SOURCE_DIR)/inc)
add_executable(${PROJECT_NAME} main.cpp ${SOURCE_DIR})

src/hello.cpp

#include <iostream>


void hello()
{
    std::cout << "hello cmake " << std::endl;
}

inc/hello.hpp

void hello();

构建、编译与运行

$ mkdir build && cd build && cmake .. && make && ../bin/hello_v2

构建hello_v3项目

项目以及内容如下

文件目录

hello_v3
├── CMakeLists.txt
├── example
│ ├── CMakeLists.txt
│ └── main.cpp
├── inc
│ └── hello.hpp
└── src
├── CMakeLists.txt
└── hello.cpp

example/main.cpp

#include <iostream>
#include "hello.hpp"


int main(int argc, char* argv[])
{
    hello();
    return 0;
}

inc/hello.hpp

void hello();

src/hello.cpp

#include <iostream>


void hello()
{
    std::cout << "hello cmake " << std::endl;
}

example/CMakeLists.txt

cmake_minimum_required(VERSION 3.16)


project(hello_v3_example)


set(EXECUTABLE_OUTPUT_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../bin)
file(GLOB SOURCE_FLIE "${CMAKE_CURRENT_SOURCE_DIR}/*.cpp"
                        ./*.cpp)


link_libraries(${CMAKE_CURRENT_SOURCE_DIR}/../lib)   
add_executable(${PROJECT_NAME} ${SOURCE_FLIE})

target_link_libraries(${PROJECT_NAME} hello)   
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../inc)      

src/CMakeLists.txt

cmake_minimum_required(VERSION 3.16)

# 设置so库生成路径
set(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib)

# 定义了SRC_LIST变量，包含当前目录下所有的源文件
aux_source_directory(. SRC_LIST)

# 编译动态库
add_library(hello SHARED ${SRC_LIST})

# 配置头文件信息
include_directories(${PROJECT_SOURCE_DIR}/inc)

CMakeLists.txt

cmake_minimum_required(VERSION 3.15)


project(hello_v3)

add_subdirectory(example)

add_subdirectory(src)

构建、编译与运行

$ mkdir build && cd build && cmake .. && make && ../bin/hello_v3_example

编译后目录

├── bin
│ └── hello_v3_example
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ ├── example
│ ├── Makefile
│ └── src
├── CMakeLists.txt
├── example
│ ├── CMakeLists.txt
│ └── main.cpp
├── inc
│ └── hello.hpp
├── lib
│ └── libhello.so
└── src
├── CMakeLists.txt
└── hello.cpp

设置编译选项

设置CMAKE_CXX_FLAGS

C++编译器参数选项，只在当前CMakeLists.txt中生效；多个CMakeLists.txt中，则每个CMakeLists.txt都需要单独指定

# -fno-exceptions   禁用运行时类型信息
# -fno-rtti         禁用异常机制
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -O3 -Wall -fno-exceptions -fno-rtti")

• add_comile_options 全局有效

  add_compile_options(-std=c++11 -Wall -Werror)
  

debug 和 release

if(NOT CMAKE_BUILD_TYPE)
    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
endif()

if(CMAKE_BUILD_TYPE AND (CMAKE_BUILD_TYPE STREQUAL "Debug"))
    SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -ggdb")
else()
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3 -Wall")
endif()

指定编译器路径

SET(CMAKE_C_COMPILER "/usr/bin/gcc")
SET(CMAKE_CXX_COMPILER "/usr/bin/g++")

CMakeLists.txt

cmake_minimum_required(VERSION 3.15)

SET(CMAKE_C_COMPILER "/usr/bin/gcc")
SET(CMAKE_CXX_COMPILER "/usr/bin/g++")

project(hello)

if(NOT CMAKE_BUILD_TYPE)
    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
endif()

if(CMAKE_BUILD_TYPE AND (CMAKE_BUILD_TYPE STREQUAL "Debug"))
    message("Debug mode:${CMAKE_CXX_FLAGS_DEBUG}")
    SET(CMAKE_CXX_FLAGS_DEBUG "$ENV{CXXFLAGS} -O0 -Wall -g -ggdb")
else()
# -fno-exceptions   禁用运行时类型信息
# -fno-rtti         禁用异常机制
    message("Release mode:${CMAKE_CXX_FLAGS_RELEASE}")
	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -O3 -Wall -fno-exceptions -fno-rtti")

endif()

set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/../bin)
add_executable(hello hello.cpp)

• 清理后，继续构建、编译与运行

$ mkdir build && cd build
$ cmake -DCMAKE_BUILD_TYPE=Debug .. && make
$ ./hello

编译后文件结构如下：
├── bin
│ └── hello
├── build
│ ├── CMakeCache.txt
│ ├── CMakeFiles
│ ├── cmake_install.cmake
│ └── Makefile
├── CMakeLists.txt
├── hello.cpp
└── Makefile