CMake使用记录

使用CMake写工程管理真的很方便，配合make或者ninja工具，用起来确实爽。

这里记录一个简单的使用示例，实现代码的分层管理。这里有CMake的教程Introduction · Modern CMake (modern-cmake-cn.github.io)。

cmake文件的标准步骤就是下面几个步骤：

1. 确定cmake的最低版本要求；
2. 确定project的名字；
3. 确定需要加入编译的源文件列表；
4. 确定需要加入编译的头文件路径清单；
5. 确定最终输出的可执行文件/库文件；
6. 确定project/target需要加入链接的库。

我这里实现一个主cmake文件以及3个子模块。

先确定目录分层

• main目录，存放可执行文件的输出；
• sub1目录，编译成sub1库，供main链接使用；
• sub2目录，编译成sub2库，供sub1和main链接使用。

# tree -a
.
├── CMakeLists.txt
├── build-target.txt
├── main
│   ├── CMakeLists.txt
│   └── main.c
├── sub1
│   ├── CMakeLists.txt
│   ├── sub1.c
│   └── sub1.h
└── sub2
    ├── CMakeLists.txt
    ├── sub2.c
    └── sub2.h

 

根CMakeLists.txt文件

cmake_minimum_required(VERSION 3.22 FATAL_ERROR)

set(CMAKE_C_STANDARD 99)
set(CMAKE_CXX_STANDARD 17)

project(hello
    VERSION 1.0
    LANGUAGES C CXX ASM)

set(CMAKE_EXPORT_COMPILE_COMMANDS OFF)
set(CMAKE_VERBOSE_MAKEFILE OFF)


add_subdirectory(main)
add_subdirectory(sub1)
add_subdirectory(sub2)

 

主目录下的文件详情

#include <stdio.h>
#include "sub1.h"
#include "sub2.h"


void function_defined_in_main(void) {
    printf("function_defined_in_main() invoked.\n");
}

int main(void) {
    printf("enter main function.\n");

    printf("invoke sub1() in main.\n");
    sub1();

    printf("invoke sub2() in main.\n");
    sub2();
    
    printf("exit main function.\n");
    
    printf("press Enter key to exit.\n");
    getchar();
    return 0;
}

cmake_minimum_required(VERSION 3.22)

set(TARGET "main")
project(${TARGET} C CXX ASM)


# 可执行输出
add_executable(${TARGET} ${CMAKE_CURRENT_LIST_DIR}/main.c)

# 目标依赖的头文件路径
target_include_directories(${TARGET} PUBLIC
    ${CMAKE_CURRENT_LIST_DIR}/../sub1
    ${CMAKE_CURRENT_LIST_DIR}/../sub2
    ${CMAKE_CURRENT_LIST_DIR})

# 目标链接需要的库
target_link_libraries(${TARGET} PRIVATE sub1 sub2)

# 指明优先在当前路径下查找库
target_link_directories(${TARGET} PRIVATE ${CMAKE_CURRENT_LIST_DIR})

 

目录sub1下的文件详情

cmake_minimum_required(VERSION 3.22)

set(TARGET "sub1")
project(${TARGET} C CXX ASM)


add_library(${TARGET} STATIC ${CMAKE_CURRENT_LIST_DIR}/sub1.c)

# 目标依赖的头文件路径
target_include_directories(${TARGET} PUBLIC
    ${CMAKE_CURRENT_LIST_DIR}
    ${CMAKE_CURRENT_LIST_DIR}/../sub2)

#include <stdio.h>
#include "sub2.h"

void function_defined_in_sub1(void) {
    printf("function_defined_in_sub1() invoked.\n");
}

void sub1(void) {
    printf("enter sub1 function.\n");
    printf("invoke sub2() in library \"sub1\"\n");
    sub2();
    printf("exit sub1 function.\n");
}

#ifndef __SUB1_H__
#define __SUB1_H__


void sub1(void);

#endif/*__SUB2_H__*/

 

目录sub2下的文件详情

cmake_minimum_required(VERSION 3.22)

set(TARGET "sub2")
project(${TARGET} C CXX ASM)


add_library(${TARGET} STATIC ${CMAKE_CURRENT_LIST_DIR}/sub2.c)


# 目标依赖的头文件路径
target_include_directories(${TARGET} PUBLIC
    ${CMAKE_CURRENT_LIST_DIR})

#include <stdio.h>

extern void function_defined_in_main(void);
extern void function_defined_in_sub1(void);

void sub2(void) {
    printf("enter sub2 function.\n");
    printf("invoke function_defined_in_main in library \"sub2\".\n");
    function_defined_in_main();
    printf("invoke function_defined_in_sub1 in library \"sub2\".\n");
    function_defined_in_sub1();
    
    printf("exit sub2 function.\n");
}

#ifndef __SUB2_H__
#define __SUB2_H__


void sub2(void);

#endif/*__SUB2_H__*/

 

编译命令

在根目录下执行cmake编译，将输出全部指定在 build 目录下。

• “cmake -B build”表示将所有输出放到 build 目录下。
• “./build/main/mian”是启动可执行文件。

# cmake -B build . && cd ./build && make && cd .. && ./build/main/main

 上面的命令行有些繁杂，我们可以做的更加精简：

# cmake -B build . && cmake --build build

 

输出结果

root@lxxx:/mnt/d/workspace/hello# ls
CMakeLists.txt  build-target.txt  main  sub1  sub2
root@lxxx:/mnt/d/workspace/hello# cmake -B build . && cd ./build && make && cd .. && ./build/main/main
-- The C compiler identification is GNU 11.4.0
-- The CXX compiler identification is GNU 11.4.0
-- The ASM compiler identification is GNU
-- Found assembler: /usr/bin/cc
-- 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
-- Configuring done
-- Generating done
-- Build files have been written to: /mnt/d/workspace/hello/build
[ 16%] Building C object sub2/CMakeFiles/sub2.dir/sub2.c.o
[ 33%] Linking C static library libsub2.a
[ 33%] Built target sub2
[ 50%] Building C object sub1/CMakeFiles/sub1.dir/sub1.c.o
[ 66%] Linking C static library libsub1.a
[ 66%] Built target sub1
[ 83%] Building C object main/CMakeFiles/main.dir/main.c.o
[100%] Linking C executable main
[100%] Built target main
enter main function.
invoke sub1() in main.
enter sub1 function.
invoke sub2() in library "sub1"
enter sub2 function.
invoke function_defined_in_main in library "sub2".
function_defined_in_main() invoked.
invoke function_defined_in_sub1 in library "sub2".
function_defined_in_sub1() invoked.
exit sub2 function.
exit sub1 function.
invoke sub2() in main.
enter sub2 function.
invoke function_defined_in_main in library "sub2".
function_defined_in_main() invoked.
invoke function_defined_in_sub1 in library "sub2".
function_defined_in_sub1() invoked.
exit sub2 function.
exit main function.
press Enter key to exit.

root@lxxx:/mnt/d/workspace/hello#

 

 

特此记录。