Cmake learning

CMake brief introduction

Easy to use , Can cross platform , Build the project compilation environment . Especially better than writing directly Makefile Simple （ When building a large project, compile , Need to write a lot of File Dependencies ）, It can be done by simple CMake Generate responsible Makefile file .

CMake install

ubuntu On the direct execution of sudo apt install cmake installation is complete , Can pass cmake -version View its version ：

CMake Brief introduction

cmake_minimum_required (VERSION 3.0) # requirement cmake Minimum version number 
project (demo) 	#  Define the name of the current project 
set(CMAKE_BUILD_TYPE "Debug")	#  Set up debug Pattern , Without this line, you cannot debug and set breakpoints 
set(CMAKE_CXX_FLAGS ${
    CMAKE_CXX_FLAGS} -g)
add_executable(main main.c)
#  Enter the subdirectory to execute  CMakeLists.txt file   there lib and tests There are compiled code files 
add_subdirectory(lib)
add_subdirectory(tests)

If there are multiple source files to compile , Can be added to add_executable(main main.cpp test.cpp) In the list , But if there are too many source files , Add one by one to add_executable In the source file list of , It's too much trouble , You can use
aux_source_directory(dir var) To define the source file list , Use as follows ：

cmake_minimum_required (VERSION 3.0)
project (demo)
aux_source_directory(. SRC_LIST) #  Defining variables , Store all source files in the current directory 
add_executable(main ${
    SRC_LIST})

aux_source_directory() There are also disadvantages , It will add all source files in the specified directory , We may add some files we don't need , Now we can use it set Command to create a new variable to store the required source file , as follows ：

cmake_minimum_required (VERSION 3.0)
project (demo)
set( SRC_LIST
	./main.cpp
	./test.cpp)
add_executable(main ${
    SRC_LIST})

Examples of use

muduo The server of the network library , Commands when compiling links ：

stay CMakeLists.txt Writing on ：

cmake_minimum_required(VERSION 3.0)

#  The name of the project , Not an executable name 
project(main)

#  Configure compile options 
set(CMAKE_CXX_FLAGS ${
    CMAKE_CXX_FLAGS} -g)

#  Configure header file search path 
# include_directories()

#  Configuration library file search path 
# link_directories()

#  Set the list of source files to compile 
set(SRC_LIST ./muduo_server.cpp)

#  Set the final storage path of the executable 
set(EXECUTABLE_OUTPUT_PATH ${
    PROJECT_SOURCE_DIR}/bin)

#  Put all the source file names under the specified path into the variable name SRC_LIST Inside 
# aux_source_directory(. SRC_LIST)

#  The resulting file ,  By whom 
add_executable(server ${
    SRC_LIST})

#  Express server This object program , Connection required muduo_net muduo_base pthread These three library files 
target_link_libraries(server muduo_net muduo_base pthread)

stay build Execute under folder cmake …

Re execution make

CMakeLists.txt The final generated executable file written in bin Under the table of contents , So go to bin Inside .

Run the example ：

Why CMake

Someone will ask. , I have only one cpp Source file , Use CMake After that, so many files were generated , That looks troublesome ：

reason ： In the actual development process , A project roughly includes the following modules ：
The final generated executable 、 Intermediate library file 、 The header file 、 Source file 、CMake Generated files 、 The test file 、 Third party library files 、CMake file , Automatic compilation of script files , So many files , If you write makefile It will be more troublesome , While using CMake It's very convenient .

CMake Common predefined variables

PROJECT_NAME :  adopt  project()  Specify project name 

PROJECT_SOURCE_DIR :  The root directory of the project 

PROJECT_BINARY_DIR :  perform  cmake  Directory of commands 

CMAKE_CURRENT_SOURCE_DIR :  At present  CMakeList.txt  Directory of files 

CMAKE_CURRENT_BINARY_DIR :  Compile Directory , You can use  add subdirectory  To modify the 

EXECUTABLE_OUTPUT_PATH :  Binary executable output location 

LIBRARY_OUTPUT_PATH :  Library file output location 

BUILD_SHARED_LIBS :  The default library compilation method  ( shared  or  static ) , The default is  static

CMAKE_C_FLAGS :  Set up  C  Compilation options 

CMAKE_CXX_FLAGS :  Set up  C++  Compilation options 

CMAKE_CXX_FLAGS_DEBUG :  Set compilation type  Debug  Compile options for 

CMAKE_CXX_FLAGS_RELEASE :  Set compilation type  Release  Compile options for 

CMAKE_GENERATOR :  Compiler name 

CMAKE_COMMAND : CMake  The full path of the executable itself 

CMAKE_BUILD_TYPE :  Version generated by project compilation , Debug / Release