使用Cmake生成makefile

转自：http://wenx05124561.blog.163.com/blog/static/1240008052012412236777/

CMake是一个跨平台的安装(编译)工具,可以用简单的语句来描述所有平台的安装(编译过程)。他能够输出各种各样的makefile或者project文件,能测试编译器所支持的C++特性。只是 CMake 的组态档取名为 CmakeLists.txt。Cmake 并不直接建构出最终的软件，而是产生标准的建构档（如 linux 的 Makefile 或 Windows Visual C++ 的 projects/workspaces），然后再依一般的建构方式使用。

在 linux 平台下使用 CMake 生成 Makefile 并编译的流程如下:

1. 编写 CmakeLists.txt。
2. 执行命令 “cmake PATH” 或者 “ccmake PATH” 生成 Makefile ( PATH 是 CMakeLists.txt 所在的目录 )。
3. 使用 make 命令进行编译

工程实例：

一. 编写各层CMakeLists.txt

主目录的主程序main.cpp

#include "hello.h"

extern Hello hello;

int main()

{

  hello.Print();

  return 0;

}

主目录的CMakeLists.txt

# to the root binary directory of the project as ${MAIN_BINARY_DIR}.

project (MAIN)

#version support

cmake_minimum_required(VERSION 2.8)

# Recurse into the "Hello" and "Demo" subdirectories.  This does not actually

# cause another cmake executable to run.  The same process will walk through

# the project's entire directory structure.

add_subdirectory (Hello)

add_subdirectory (Demo)

# Make sure the compiler can find include files from our Hello library.

include_directories (${MAIN_SOURCE_DIR}/Hello)

# Make sure the linker can find the Hello Demo library once it is built.

link_directories (${HELLO_BINARY_DIR}/Hello)

link_directories (${HELLO_BINARY_DIR}/Demo)

#define the source coedes of current directory as DIR_SRCS

AUX_SOURCE_DIRECTORY(. DIR_SRCS)

# Add executable called "MAIN" that is built from the source files

add_executable (Main ${DIR_SRCS})

# Link the executable to the Hello Demo library.

target_link_libraries (Main Hello Demo)

定义项目名project(MAIN),使得当前目录可以用${MAIN_SOURCE_DIR}，由于有2个子目录，所以需要add_subdirectory它们。由于主程序会使用到其他库，因而也需要指定连接库所在目录。

主目录下的作用是利用add_executable将当前目录下的源文件编译成Main程序，然后通过target_link_libraries链接Hello和Demo库。由于主程序文件使用了hello.h文件，所以要include_directories该目录。

---------------------------------------------------------------------------------------------------

子目录Demo的子程序demo.c

#include "hello.h"

Hello hello;

子目录Demo的CMakeLists.txt

# Make sure the compiler can find include files from our Hello library.

include_directories (${MAIN_SOURCE_DIR}/Hello)

#define the source coedes of current directory as DIR_DEMO_SRCS

AUX_SOURCE_DIRECTORY(. DIR_DEMO_SRCS)

# Add library called "Demo" that is built from the source files

add_library  (Demo ${DIR_DEMO_SRCS})

Demo目录下的CMakeLists主要作用是利用add_library将当前目录源码编译成Demo库，由于该库使用到hello.h文件,所以要include_directories该目录。

---------------------------------------------------------------------------------------------------

子目录Hello的子程序hello.h

#ifndef _hello_h

#define _hello_h

class Hello

{

public:

  void Print();

};

#endif

子目录Hello的子程序hello.c

#include "hello.h"

#include <stdio.h>

void Hello::Print()

{

  printf("Hello, World! ");

}

子目录Hello的CMakeLists.txt

#define the source coedes of current directory as DIR_HELLO_SRCS

AUX_SOURCE_DIRECTORY(. DIR_HELLO_SRCS)

# Add library called "hello" that is built from the source files

add_library (Hello ${DIR_HELLO_SRCS})

Hello目录下的CMakeLists主要作用是利用add_library将当前目录源码编译成Hello库。

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二. 执行cmake命令

至此我们完成了项目中所有 CMakeLists.txt 文件的编写,进入目录 step2 中依次执行命令 

#cmake  .  

默认当前目录，生产makefile

#make 

最后编译程序