Get started quickly cmake

Use Cmake It is convenient for us to configure C++ file , The efficiency of compilation is greatly improved , but Cmakelists Some of the key words in the are written and used in a similar way , There may be a bit of confusion for novices who haven't been in touch . This article will introduce the simple CmakeLists File configuration method , I hope you can compile your own C++ Engineering documents .

1. The file path is as follows ：

2. Header files and cpp The contents of the document are as follows ：

hello.h

#include <iostream>

void say_hello();

hello.cpp

#include "hello.h"

void say_hello(){
    std::cout<<"hello_world"<<std::endl;
}

test.cpp

#include <opencv2/opencv.hpp>
#include "hello.h"
using namespace cv;
int main(){
    cv::Mat frame = cv::imread("./dog.jpg");
    cv::imshow("test", frame);
    cv::waitKey(0);
    say_hello();
    say_hello();
    getchar();
    return 0;
}

In this case test.cpp call opencv library , And my own hello library , We can write according to our own needs Cmakelists The documents are as follows ：

2.1 Manually add ：

Use include_directories and target_link_libraries Add header and library files manually

Do not select build hello The library files , need hello.cpp Added to the add_executable

To be sure ：project Inside opencvTest Project name ,add_executable and target_link_libraries Inside main Is the executable file name , You can have the same name

cmake_minimum_required(VERSION 3.1)

project(opencvTest)
# Add header file path manually  
include_directories("/usr/include/opencv4")
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
add_executable(main hello.cpp test.cpp)

# Add library manually
target_link_libraries(main opencv_calib3d;opencv_core;opencv_gapi;opencv_highgui;opencv_imgcodecs;opencv_imgproc;opencv_video;opencv_videoio)

2.2 Manually add , And generate hellolib：

At this time in add_executable No need to add hello.cpp, But need to be in target_link_libraries Add generated hellolib library , Libraries can be separated by spaces or semicolons

cmake_minimum_required(VERSION 3.1)

project(opencvTest)
# Add header file path manually  
include_directories("/usr/include/opencv4")
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
# Generate static or dynamic libraries
add_librarY(hellolib SHARED hello.cpp)

add_executable(main test.cpp)

# Add library manually , Contains the libraries generated above
target_link_libraries(main hellolib opencv_calib3d;opencv_core;opencv_gapi;opencv_highgui;opencv_imgcodecs;opencv_imgproc;opencv_video;opencv_videoio)

2.3 Use find method ：

${OpenCV_INCLUDE_DIRS} Is the header file path ,${OpenCV_LIBS} Found for opencv library

message For output find_package Information about .

To sum up , The search mode is divided into find_package->include_directories->target_link_libraries

cmake_minimum_required(VERSION 3.1)

project(opencvTest)
# Look for libraries in the system directory
find_package(OpenCV REQUIRED)

message(STATUS "OpenCV library status:")
message(STATUS "    version: ${OpenCV_VERSION}")
message(STATUS "    libraries: ${OpenCV_LIBS}")
message(STATUS "    include path: ${OpenCV_INCLUDE_DIRS}")
# Add the header file path
include_directories(${OpenCV_INCLUDE_DIRS})

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)

add_library(hellolib SHARED hello.cpp)

add_executable(main test.cpp)

# Link library
target_link_libraries(main hellolib ${OpenCV_LIBS})
 

2.4 about hpp File status ：

2.4.1. Can be hpp File put in include Folder , Use as header file

cmake_minimum_required(VERSION 3.1)

project(opencvTest)
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
add_executable(main test.cpp)

2.4.2. Can also be hpp The file is placed in the file to be compiled cpp Files are compiled under the same level directory

cmake_minimum_required(VERSION 3.1)

project(opencvTest)
add_executable(main hello.hpp test.cpp)

That's right cmakelists A brief summary of grammar , For small projects, the above configuration can be used cmakelists file , Welcome to discuss .