C++_分离编译与Cmake

C++工程结构

目录结构

小型项目， 可以简单地将 .h 与 .c 这两类源文件分别归纳在两个独立的目录 include 与 src 中
稍微大一些的项目 能够以模块为单位，以库的形式进行抽象的实现，可以统一放在名为 libs 的目录下进行管理

项目的编译流程

01.GCC命令行编译 文件 src/main.c 为程序入口 main 函数的所在文件
02.使用 Makefile 进行结构化编译
03.使用 CMake 进行跨平台的自动化构建 CMake（Cross-platform Make）

静态库 --动态库 共享链接库
Linux下的共享链接库主要放在/lib目录下，以lib.so.为典型的文件

文件目录

build
config
-- config_test.yaml
include
-- read_from_yaml.h
src
-- main.cpp
-- read_from_yaml.cpp
CMakeLists.txt
0_build.sh
1_run.sh

各自内容

内容详解

config_test.yaml

%YAML:1.0
name: 'test'
grade: 12
score: 9.1
input_path: '../data/test.txt'

read_from_yaml.h

// include guard
#ifndef IMG_DATA_READ_H
#define IMG_DATA_READ_H

include

include

include

include

include <opencv2/opencv.hpp>

include <opencv2/core.hpp>

using namespace std;

typedef struct Params_in{
std::string name;
int grade;
float score;
std::string input_path;
} Params;
bool read_param_from_yaml(std::string yaml_f_nm, Params &in_params);
void show_param(Params &in_params);
#endif

read_from_yaml.cpp

include "read_from_yaml.h"

bool read_param_from_yaml(std::string yaml_f_nm, Params &in_params)
{
cv::FileStorage file_conf(yaml_f_nm,cv::FileStorage::READ);
if(! file_conf.isOpened() ){
std::cout << "Failed open " << yaml_f_nm << endl;
return false;
}
else stf:cout << "Success open " << yaml_f_nm << endl;
file_conf["name"] >> in_params.name ;
file_conf["grade"] >> in_params.grade ;
file_conf["score"] >> in_params.score ;
file_conf["input_path"] >> in_params.input_path ;
//file_conf.release()
return true;
}
void show_param(Params &in_params)
{
std::cout << "name " << in_params.name << endl;
std::cout << "grade " << in_params.grade << endl;
std::cout << "score " << in_params.score << endl;
std::cout << "input_path " << in_params.input_path << endl;
}

main.cpp

include

include

include

include

include <opencv2/opencv.hpp>

include <opencv2/core.hpp>

include "read_from_yaml.h"

using namespace std;

int main(int argc, char** argv)
{
std:string cfg_path = "./config/config_test.yaml";
Params in_params;
if(! read_param_from_yaml(cfg_path, in_params)){
return false;
}
show_param(in_params);
return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.0.2)
set(PROJECT_NAME config_read)
set(CMAKE_CXX_STANDARD 11)
set(OpenCV2_DIR /usr/share/OpenCV)
project(${PROJECT_NAME})

find_package(OpenCV REQUIRED)
message(STATUS " version: ${OpenCV_VERSION}")
message(STATUS " libraries: ${OpenCV_LIBS}")
message(STATUS " includ: ${OpenCV_INCLUDE_DIRS}")

include_directories(
./include
${OpenCV_INCLUDE_DIRS}
${OpenCV_INCLUDE_DIRS}/opencv2
)
link_libraries( ${OpenCV_LIBS})
###########
## Build ##
###########

Specify additional locations of header files

Your package locations should be listed before other locations

include_directories(
./include
${OpenCV_INCLUDE_DIRS}
)
## Declare a C++ executable

add_executable(\({PROJECT_NAME} src/main.cpp src/read_from_yaml.cpp ) ## Specify libraries to link a library or executable target against target_link_libraries(\){PROJECT_NAME}
${OpenCV_LIBRARIES}
)

0_build.sh

cd build && rm -rf ./* && cmake .. && make all -j16

1_run.sh

./build/config_read

执行步骤

sh 0_build.sh
sh 1_run.sh
执行说明
mkdir build && cd build 创建并进入用于存放编译结果文件的临时目录
cmake .. 生成本地化构建项目

说明

静态库与动态库构建
find_library ## 该命令用于搜索指定动态文件路径
add_library ## add_library(Hello hello.cxx) #将hello.cxx编译成静态库如libHello.a
include_directories ## include_directories：指定头文件的搜索路径，相当于指定gcc的-I参数
link_directories ## link_directories：动态链接库或静态链接库的搜索路径，相当于gcc的-L参数 link_directories仅对其后面的targets起作用
add_executable ## add_executable：编译可执行程序，指定编译--设置二进制目标文件的依赖
target_include_directories ## 指定目标包含的头文件路径
target_link_libraries ## target_link_libraries：添加链接库,相同于指定-l参数
同一目录，多个源文件
# 指定生成目标
add_executable(Demo main.cpp myMath.cpp)
多个目录，多个源文件
先将 math 目录里的文件编译成静态库再由 main 函数调用
# 添加 math 子目录
add_subdirectory(math)
# 添加链接库
target_link_libraries(demo MathFunctions)

子目录 CMakeLists.txt
# 生成链接库 add_library 将 DIR_LIB_SRCS 目录中的源文件编译为静态链接库
add_library (MathFunctions ${DIR_LIB_SRCS})

参考

https://docs.opencv.org/3.2.0/d4/da4/group__core__xml.html
https://github.com/dev-cafe/cmake-cookbook
https://www.mianshigee.com/tutorial/CMake-Cookbook/