cmake 的使用

决定代码的组织方式及其编译方式，也是程序设计的一部分。因此，我们需要cmake和autotools这样的工具来帮助我们构建并维护项目代码。cmake和autotools正是makefile的上层工具，它们的目的正是为了产生可移植的makefile，并简化自己动手写makefile时的巨大工作量。

下载 cmake

http://www.cmake.org/cmake/resources/software.html

#tar -xvf cmake-3.22.0-rc2.tar.gz        
#cd cmake-3.22.0-rc2
#./bootstrap
#make
#make install
 
cmake 会默认安装在 /usr/local/bin 下面

建立工程

q@ubuntu:~/test_cmake_prj$ tree .
.
├── build
├── CMakeLists.txt
├── main.c
└── src
    ├── CMakeLists.txt
    ├── test.c
    └── test.h

2 directories, 5 files

q@ubuntu:~/test_cmake_prj$ cat CMakeLists.txt 
PROJECT(MAIN_prj) # 项目名称
CMAKE_MINIMUM_REQUIRED(VERSION 2.6) # cmake最低版本需求，不加入此行会受到警告信息
ADD_SUBDIRECTORY(src) # 指明本项目包含一个子目录src, 进入目录src对其中的CMakeLists.txt进行解析
AUX_SOURCE_DIRECTORY(. DIR_SRCS) # 把当前目录(.)下所有源代码文件和头文件加入变量DIR_SRCS
ADD_EXECUTABLE(main ${DIR_SRCS})
# 生成应用程序 main
TARGET_LINK_LIBRARIES(main Test) # 指明可执行文件 main 需要连接一个名为Test的链接库

q@ubuntu:~/test_cmake_prj$ cat main.c 
#include<stdio.h>
int main(void)
{
    char s[] = "Hello,World\n";
    printf(s);
    println(s);
    return 0;
}

q@ubuntu:~/test_cmake_prj$ cat src/CMakeLists.txt 
AUX_SOURCE_DIRECTORY(. DIR_TEST1_SRCS) # 把当前目录(.)下所有源代码文件和头文件加入变量DIR_TEST1_SRCS
ADD_LIBRARY(Test ${DIR_TEST1_SRCS}) # 将src目录中的源文件编译为共享库

q@ubuntu:~/test_cmake_prj$ cat src/test.c
#include <stdio.h>
#include "test.h"
void println()
{
	printf("PI=%.2f\n", PI);
}

q@ubuntu:~/test_cmake_prj$ cat src/test.h
#define PI 3.14
void println();

生成 Makefile - cmake

注意事项，尽量在新建的 build 目录中进行生成操作，注意最后参数 ..为上级目录。

q@ubuntu:~/test_cmake_prj/build$ sudo ../../cmake-3.22.2-linux-x86_64/bin/cmake ..
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/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: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Deprecation Warning at CMakeLists.txt:2 (CMAKE_MINIMUM_REQUIRED):
  Compatibility with CMake < 2.8.12 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.


-- Configuring done
-- Generating done
-- Build files have been written to: /home/q/test_cmake_prj/build

生成位置如下：

q@ubuntu:~/test_cmake_prj/build$ ls
CMakeCache.txt  CMakeFiles  cmake_install.cmake  Makefile  src

make

运行