Cmake basic learning

CMake brief introduction

CMake It's a cross platform 、 Open source build system , A set of software construction 、 test 、 Packaged software . It uses configuration files independent of the platform and compiler to control the software compilation process .

One First time to know CMake

Use a very simple example ：
Under the new project folder , Create the following two files

$ tree
.
├── CMakeLists.txt
└── main.cpp

CMakelists.txt The contents of the file in are as follows

# Set the minimum version of CMake that can be used
# To find the cmake version run
# $ cmake --version
cmake_minimum_required(VERSION 3.5)

# Set the project name
project (hello_cmake)

# Add an executable
add_executable(hello_cmake main.cpp)

main.cpp Is a simple C++ Program

#include<iostream>
using namespace std;
int main(){
    
    cout <<" hello word !"<<endl;
    return 0;
}

About CMakelists.txt We will explain the contents in later , Let's compile and run the whole program first .

Binary Directory

function cmake command The root folder or top-level folder of is called CMAKE_BINARY_DIR, Is the root folder of all binaries .CMake And support to build and generate binary files in place , It also supports the construction and generation of binary files outside the source code .

In place construction

Build in place will generate all temporary files in the folder where the source code is located , Make the source code and temporary files mixed together , This will be very inconvenient .
We execute cmake . command , Pay attention to the symbols “ . ” Means to execute in the current directory .

$ cmake .
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /home/panlichen/miniconda3/envs/oneflow-dev-gcc7-v2/bin/x86_64-conda_cos6-linux-gnu-cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /home/panlichen/miniconda3/envs/oneflow-dev-gcc7-v2/bin/x86_64-conda_cos6-linux-gnu-c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/panlichen/zrk/hello_cmake

$ tree
.
├── CMakeCache.txt
├── CMakeFiles
│   ├── 3.18.2
│   │   ├── CMakeCCompiler.cmake
│   │   ├── CMakeCXXCompiler.cmake
│   │   ├── CMakeDetermineCompilerABI_C.bin
│   │   ├── CMakeDetermineCompilerABI_CXX.bin
│   │   ├── CMakeSystem.cmake
│   │   ├── CompilerIdC
│   │   │   ├── a.out
│   │   │   ├── CMakeCCompilerId.c
│   │   │   └── tmp
│   │   └── CompilerIdCXX
│   │       ├── a.out
│   │       ├── CMakeCXXCompilerId.cpp
│   │       └── tmp
│   ├── cmake.check_cache
│   ├── CMakeDirectoryInformation.cmake
│   ├── CMakeOutput.log
│   ├── CMakeTmp
│   ├── hello_cmake.dir
│   │   ├── build.make
│   │   ├── cmake_clean.cmake
│   │   ├── DependInfo.cmake
│   │   ├── depend.make
│   │   ├── flags.make
│   │   ├── link.txt
│   │   └── progress.make
│   ├── Makefile2
│   ├── Makefile.cmake
│   ├── progress.marks
│   └── TargetDirectories.txt
├── cmake_install.cmake
├── CMakeLists.txt
├── main.cpp
└── Makefile

8 directories, 28 files

It can be seen that it has been successfully generated makefile file , Next we make once , And implement

$ make
$ ./hello_cmake
 hello word !

When modifying code , There is no increase or decrease in source file modification CMakeLists.txt Just... Again make

Out of source construction （ recommend ）

Build out of source , You can create a single build folder , This folder can be located anywhere on the file system . All temporary build target files are located in this directory , To keep the source directory structure clean .

We create a build Folder , stay build Execute under folder command ：
cmake + CMakeLists.txt Location path

$ tree ..
..
├── build
├── CMakeLists.txt
└── main.cpp


$ cmake .. 
-- The C compiler identification is GNU 7.3.0
-- The CXX compiler identification is GNU 7.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /home/panlichen/miniconda3/envs/oneflow-dev-gcc7-v2/bin/x86_64-conda_cos6-linux-gnu-cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /home/panlichen/miniconda3/envs/oneflow-dev-gcc7-v2/bin/x86_64-conda_cos6-linux-gnu-c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/panlichen/zrk/hello_cmake/build

$ make
Scanning dependencies of target hello_cmake
[ 50%] Building CXX object CMakeFiles/hello_cmake.dir/main.cpp.o
[100%] Linking CXX executable hello_cmake
[100%] Built target hello_cmake

$ ./hello_cmake 
 hello word !

After off source construction , The directory structure is as follows

$ tree ..
..
├── build
│   ├── CMakeCache.txt
│   ├── CMakeFiles
│   │   ├── 3.18.2
│   │   │   ├── CMakeCCompiler.cmake
│   │   │   ├── CMakeCXXCompiler.cmake
│   │   │   ├── CMakeDetermineCompilerABI_C.bin
│   │   │   ├── CMakeDetermineCompilerABI_CXX.bin
│   │   │   ├── CMakeSystem.cmake
│   │   │   ├── CompilerIdC
│   │   │   │   ├── a.out
│   │   │   │   ├── CMakeCCompilerId.c
│   │   │   │   └── tmp
│   │   │   └── CompilerIdCXX
│   │   │       ├── a.out
│   │   │       ├── CMakeCXXCompilerId.cpp
│   │   │       └── tmp
│   │   ├── cmake.check_cache
│   │   ├── CMakeDirectoryInformation.cmake
│   │   ├── CMakeOutput.log
│   │   ├── CMakeTmp
│   │   ├── hello_cmake.dir
│   │   │   ├── build.make
│   │   │   ├── cmake_clean.cmake
│   │   │   ├── CXX.includecache
│   │   │   ├── DependInfo.cmake
│   │   │   ├── depend.internal
│   │   │   ├── depend.make
│   │   │   ├── flags.make
│   │   │   ├── link.txt
│   │   │   ├── main.cpp.o
│   │   │   └── progress.make
│   │   ├── Makefile2
│   │   ├── Makefile.cmake
│   │   ├── progress.marks
│   │   └── TargetDirectories.txt
│   ├── cmake_install.cmake
│   ├── hello_cmake
│   └── Makefile
├── CMakeLists.txt
└── main.cpp

9 directories, 32 files