C++工程(二)：学习使用CMake构建C++工程

CMake --> Makefile/Ninja/MSVC

CMake解决了makefile、MSVC不能跨平台的问题，ninja可以适用于Linux和Windows系统

cmake -S . -B build -D  # 指定Release/Debug

cmake --build build

CMake常用语法：

• add_library
• add_executable

Example 1

• OpenCV CMake示例：

# cmake needs this line
cmake_minimum_required(VERSION 3.1)

# Define project name
project(opencv_example_project)

# Find OpenCV, you may need to set OpenCV_DIR variable
# to the absolute path to the directory containing OpenCVConfig.cmake file
# via the command line or GUI
find_package(OpenCV REQUIRED)

# If the package has been found, several variables will
# be set, you can find the full list with descriptions
# in the OpenCVConfig.cmake file.
# Print some message showing some of them
message(STATUS "OpenCV library status:")
message(STATUS "    config: ${OpenCV_DIR}")
message(STATUS "    version: ${OpenCV_VERSION}")
message(STATUS "    libraries: ${OpenCV_LIBS}")
message(STATUS "    include path: ${OpenCV_INCLUDE_DIRS}")

# Declare the executable target built from your sources
add_executable(opencv_example example.cpp)

# Link your application with OpenCV libraries
target_link_libraries(opencv_example PRIVATE ${OpenCV_LIBS})

总结Summary

CMake相较于Makefile 的优势：

• CMake可以跨平台（Makefile for Linux）
• CMake的底层即为Makefile (Darknet版本的YOLO就是用makefile来组织工程的)

应知应会

• 通过cmake --version查看CMake版本
• CMake Debug和Release设置
  • CMake默认的编译模式是Debug，Release模式的运行速度要快于Debug
• 需要注意的是：add_executable需要在target_include_directories和target_link_libraries之前
  • 添加exe之后才可以include头文件和链接库
• add_executable：添加可执行文件，add_library：生成 [STATIC | SHARED | ... ] 库文件
• CMAKE_DL_LIBS 动态库加载相关的lib
  • https://cmake.org/cmake/help/latest/variable/CMAKE_DL_LIBS.html
• CMake关于Warnings
  • https://www.foonathan.net/2018/10/cmake-warnings/
• cmake 添加头文件目录，链接动态、静态库
  • https://www.cnblogs.com/binbinjx/p/5626916.html
• 不同gcc编译器对C++版本的支持
  • https://zhuanlan.zhihu.com/p/438884346
• CMake vs Ninja
  • https://iq.opengenus.org/cmake-vs-ninja/