Basic use process of cmake

1、 Directory of complete projects

        A complete project , It should be divided into at least these parts . among ,bin Under the directory is the runnable file ,build Under the directory is the temporarily built file ,include Under the directory is the header file used ,src Under the directory is the implementation file of the header file . Of course, you can add test The test file ,third Third party library files, etc

 2、cmake Use

        cmake Easy to use , Can cross platform , Build the project compilation environment . Especially better than writing directly Makefile Simple （ In building large-scale project compilation when , Need to write a lot of File Dependencies ）, It can be done by simple CMake Generate responsible Makefile file . We often use External build ,

         Use external build , We can create a build folder that can be located anywhere on the file system . All temporary builds and target files are located in this directory , To keep the source code tree clean .（ You can specify the location of the target file ）. Take the above example ：

cd /build/              go to build Under the table of contents

cmake ..              cmake  Because of Engineering CMakeLists.txt At the previous level , So there is   ..

make                    The previous step will generate makefile file ,make perform .

3、CMakeLists.txt Compiling

cmake_minimum_required(VERSION 3.10)
# Appoint camke The smallest version of ,   You can specify the minimum to maximum version 

project(sum1)
# Set up   project name 

set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)
# Appoint   Generated executable file   Storage directory 

set(SOURCES
    src/sum.cpp)
    main.cpp)
# Create a variable , Name is SOURCES. It contains the specified cpp file 

add_executable(sum11 ${SOURCES})
# Generate an executable file with all the source files , Because it defines SOURCE Variable , So there is no need to list cpp The file 

target_include_directories(sum11
    PRIVATE
       ${PROJECT_SOURCE_DIR}/include)
# Set this executable file sum11 The path of the library to be included , Note the executable  sum11  The path of the library to be included .

  Finish writing this CMakeList.txt After the document , You can follow the step 2 Do what you say .

The above description is a simple step , With the complexity of the project , Need to write more . Summarize and distinguish some common quantities .

1、aux_source_directory(<dir> <variable>) And  set(<variable> target.cpp)

Find all source files in the directory . Collect in the specified directory Names of all source files , And store the list in the provided variable .

set(SOURCES src/sum.cpp) Collect designated The specified source file in the directory , And store . 

2、include_directories(${PROJECT_SOURCE_DIR}/include) And  

target_include_directories(sum11  PRIVATE  ${PROJECT_SOURCE_DIR}/include)

effect ： Add header file search path to source file ： Add the specified directory to the compiler's header file search path , The specified directory is interpreted as the relative path of the current source path .

first ： At present CMakeList.txt Medium All goals as well as All after its call point All targets in the added subdirectories will have header file search paths .

the second ： Designated target Include header file path .

Usage of intermediate attributes ：<INTERFACE|PUBLIC|PRIVATE> Basis of use

• PRIVATE - The directory is added to the target （ library ） In the included path of .
• INTERFACE - The directory was not added to the target （ library ） In the included path of , It links to other targets of the library （ Library or executable program ） Included in path
• PUBLIC - The directory is added to the target （ library ） In the included path of , Also added to other targets linked to this library （ Library or executable program ） In the included path of

in other words , Depending on whether the library contains this path , And whether other targets that call the library contain this path , It can be divided into three types scope.