CMake入门

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,类似UNIX下的automake

一、单个文件

main.cc

#include <stdio.h>

#include <stdlib.h>

double power(double base, int exponent)

{

    int result = base;

    int i;

    if (exponent == 0)

    {

        return 1;

    }

    for (i = 1; i < exponent; ++i)

    {

        result = result * base;

    }

    return result;

}

int main(int argc, char *argv[])

{

    if (argc < 3)

    {

        printf("Usage: %s base exponent \n", argv[0]);

        return 1;

    }

    double base = atof(argv[1]);

    int exponent = atoi(argv[2]);

    double result = power(base, exponent);

    printf("%g ^ %d is %g\n", base, exponent, result);

    return 0;

}

当前目录下的CMakeLists.txt(CMakeLists 不区分大小写)

# 版本最低要求

cmake_minimum_required(VERSION 2.8)

# 项目信息

project(Demo01)

# 指定生成目标

add_executable(Demo01 main.cc)

执行命令

cmake . # 执行cmake，自动生成对应的makefile

make # 生成二进制文件Demo01

编译输出

➜  cmakedemo cmake .

-- The C compiler identification is AppleClang 9.0.0.9000039

-- The CXX compiler identification is AppleClang 9.0.0.9000039

-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc

-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc -- works

-- Detecting C compiler ABI info

-- Detecting C compiler ABI info - done

-- Detecting C compile features

-- Detecting C compile features - done

-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++

-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -- works

-- Detecting CXX compiler ABI info

-- Detecting CXX compiler ABI info - done

-- Detecting CXX compile features

-- Detecting CXX compile features - done

-- Configuring done

-- Generating done

-- Build files have been written to: /Users/fanghao/Desktop/cmakedemo

➜  cmakedemo make

Scanning dependencies of target Demo01

[ 50%] Building CXX object CMakeFiles/Demo01.dir/main.cc.o

[100%] Linking CXX executable Demo01

[100%] Built target Demo01

➜  cmakedemo ./Demo01 5 4

5 ^ 4 is 625

二、多个文件

修改项目结构如下：

➜  cmakedemo tree

.

├── CMakeLists.txt

├── MathFunction.cc

├── MathFunctions.h

└── main.cc

0 directories, 4 files

CMakeLists.txt也应当添加多个文件

# 版本最低要求

cmake_minimum_required(VERSION 2.8)

# 命令不区分大小写

# 项目信息

project(Demo02)

#把源文件变成变量

aux_source_directory(. DIR_SRCS)

# 指定生成目标

add_executable(Demo02 ${DIR_SRCS})

三、子模块

修改项目结构如下：

➜  cmakedemo tree

.

├── CMakeLists.txt

├── main.cc

└── math

    ├── CMakeLists.txt

    ├── MathFunction.cc

    └── MathFunctions.h

1 directory, 5 files

cmakedemo目录下的CMakeLists.txt

# 版本最低要求

cmake_minimum_required(VERSION 2.8)

# 命令不区分大小写

# 项目信息

set(NAME Demo03)

project(${NAME})

# 添加math子目录，会执行math目录下的cmake

add_subdirectory(math)

# 指定生成目标

add_executable(${NAME} main.cc)

# 添加链接库

target_link_libraries(${NAME} MathFunctions)

math目录下的CMakeLists.txt

# 查找当前目录下的所有源文件

# 并将名称保存到 DIR_LIB_SRCS 变量

aux_source_directory(. DIR_LIB_SRCS)

# 生成链接库

add_library (MathFunctions ${DIR_LIB_SRCS})

此时的输出，注意编译了子模块

➜  cmakedemo cmake .

-- The C compiler identification is AppleClang 9.0.0.9000039

-- The CXX compiler identification is AppleClang 9.0.0.9000039

-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchai

ns/XcodeDefault.xctoolchain/usr/bin/cc-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchai

ns/XcodeDefault.xctoolchain/usr/bin/cc -- works-- Detecting C compiler ABI info

-- Detecting C compiler ABI info - done

-- Detecting C compile features

-- Detecting C compile features - done

-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolch

ains/XcodeDefault.xctoolchain/usr/bin/c++-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolch

ains/XcodeDefault.xctoolchain/usr/bin/c++ -- works-- Detecting CXX compiler ABI info

-- Detecting CXX compiler ABI info - done

-- Detecting CXX compile features

-- Detecting CXX compile features - done

-- Configuring done

-- Generating done

-- Build files have been written to: /Users/fanghao/Desktop/cmakedemo

➜  cmakedemo make

Scanning dependencies of target MathFunctions

[ 25%] Building CXX object math/CMakeFiles/MathFunctions.dir/MathFunction.cc.o

[ 50%] Linking CXX static library libMathFunctions.a

[ 50%] Built target MathFunctions

Scanning dependencies of target Demo03

[ 75%] Building CXX object CMakeFiles/Demo03.dir/main.cc.o

[100%] Linking CXX executable Demo03

[100%] Built target Demo03

➜  cmakedemo ./Demo03 3 4

3 ^ 4 is 81

生成的文件

➜  cmakedemo tree -L 2

.

├── CMakeCache.txt

├── CMakeFiles

│   ├── 3.11.3

│   ├── CMakeDirectoryInformation.cmake

│   ├── CMakeOutput.log

│   ├── CMakeTmp

│   ├── Demo03.dir

│   ├── Makefile.cmake

│   ├── Makefile2

│   ├── TargetDirectories.txt

│   ├── cmake.check_cache

│   ├── feature_tests.bin

│   ├── feature_tests.c

│   ├── feature_tests.cxx

│   └── progress.marks

├── CMakeLists.txt

├── Demo03

├── Makefile

├── cmake_install.cmake

├── main.cc

└── math

    ├── CMakeFiles

    ├── CMakeLists.txt

    ├── Makefile

    ├── MathFunction.cc

    ├── MathFunctions.h

    ├── cmake_install.cmake

    └── libMathFunctions.a

6 directories, 22 files

可以注意到生成了libMathFunctions.a库

三、第三方库

以glew和glfw为例

cmake_minimum_required(VERSION 3.9)

project(helloworld)

set(CMAKE_CXX_STANDARD 11)

# 自动寻找库

find_library(OPENGL opengl)

# 添加头文件

set(GLEW_H /usr/local/Cellar/glew/2.1.0/include/GL)

set(GLFW_H /usr/local/Cellar/glfw/3.2.1/include/GLFW)

include_directories(${GLEW_H} ${GLFW_H})

# 添加目标链接

set(GLEW_LINK /usr/local/Cellar/glew/2.1.0/lib/libGLEW.2.1.dylib)

set(GLFW_LINK /usr/local/Cellar/glfw/3.2.1/lib/libglfw.3.dylib)

link_libraries(${OPENGL} ${GLEW_LINK} ${GLFW_LINK})

# 执行编译命令

set(SOURCE_FILES main.cc)

add_executable(helloworld ${SOURCE_FILES})

四、小结

cmake作为跨平台的项目管理工具，相比make更加简洁易用。