当前位置:网站首页>Cmake tutorial Step2 (add Library)
Cmake tutorial Step2 (add Library)
2022-07-05 17:45:00 【It's beginning to boil】
CMake Official documents
Refer to the official cmake3.24 Course translation
https://cmake.org/cmake/help/v3.24/guide/tutorial/index.html
https://gitlab.kitware.com/cmake/cmake/-/tree/master/Help/guide/tutorial
step2
https://cmake.org/cmake/help/v3.24/guide/tutorial/Adding%20a%20Library.html
My warehouse :
https://github.com/FRBoiling/cmake-tutorial.git
Add a library
Now? , We will add a library to the project . This library will contain our own implementation of calculating the square root of numbers . then , Executable files can use this library , Instead of the standard square root function provided by the compiler .
In this tutorial , We will put the library into a file named MathFunctions In the subdirectory of . This directory contains a header file MathFunctions.h And a source file mysqrt.cxx. The source file has a name mysqrt Function of , It provides with the compiler sqrt Functions similar functions .
Add the following line CMakeLists.txt Add files to MathFunctions Catalog :
Initialize the library
Go to the project folder Step2, Create subdirectories MathFunctions, This directory contains a header file MathFunctions.h、 A source file mysqrt.cxx And a CMakeLists.txt file
mkdir Step2 Step2_build
cd Step2
mkdir MathFunctions
cd MathFunctions
touch MathFunctions.h mysqrt.cxx CMakeLists.txt
MathFunctions.h The contents are as follows :
double mysqrt(double x);
mysqrt.cxx The contents in are as follows :
#include <iostream>
// a hack square root calculation using simple operations
double mysqrt(double x)
{
if (x <= 0) {
return 0;
}
double result = x;
// do ten iterations
for (int i = 0; i < 10; ++i) {
if (result <= 0) {
result = 0.1;
}
double delta = x - (result * result);
result = result + 0.5 * delta / result;
std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
}
return result;
}
CMakeLists.txt The contents are as follows
add_library(MathFunctions mysqrt.cxx)
Project reference library
The project structure is as follows :
In order to use the new library , We will be in the top-level directory (Step2)CMakeLists.txt Add a add_subdirectory() call , In order to build a library . We add the new library to the executable , And add MathFunctions As include Catalog , So that you can find MathFunctions.h The header file . top CMakeLists.txt The last few lines of the file should now look like this :
# add the MathFunctions library
add_subdirectory(MathFunctions)
# add the executable
add_executable(Tutorial tutorial.cxx)
target_link_libraries(Tutorial PUBLIC MathFunctions)
# add the binary tree to the search path for include files
# so that we will find TutorialConfig.h
target_include_directories(Tutorial PUBLIC
"${PROJECT_BINARY_DIR}"
"${PROJECT_SOURCE_DIR}/MathFunctions"
)
1.1、 Build optional options
Now? Let's go MathFunctions The library is set to optional . For this tutorial , There is really no need to do this , But for the Bigger projects Come on , This is a common situation . The first step is at the top CMakeLists.txt Add an option to the file .
option(USE_MYMATH "Use tutorial provided math implementation" ON)
# configure a header file to pass some of the CMake settings
# to the source code
configure_file(tutorial_config.h.in tutorial_config.h)
This option will be displayed in cmake-gui and ccmake in , The default value is ON, The user can change this value . This setting will be stored in the cache , In this way, users do not need to run on the build directory every time CMake This value is set when .
1.2、 Condition building and linking
next The change is to build and link MathFunctions The library is set to condition . So , We're going to create one if Statement to check the value of this option . stay if In block , Put it in the top add_subdirectory() Commands and some additional list commands , To store the information needed to link to the Library , And take the subdirectory as include Add the directory to the tutorial target . top CMakeLists.txt The end of the file now looks like this :
if(USE_MYMATH)
add_subdirectory(MathFunctions)
list(APPEND EXTRA_LIBS MathFunctions)
list(APPEND EXTRA_INCLUDES "${PROJECT_SOURCE_DIR}/MathFunctions")
endif()
# add the executable
add_executable(Tutorial tutorial.cxx)
target_link_libraries(Tutorial PUBLIC ${EXTRA_LIBS})
# add the binary tree to the search path for include files
# so that we will find TutorialConfig.h
target_include_directories(Tutorial PUBLIC
"${PROJECT_BINARY_DIR}"
${EXTRA_INCLUDES}
)
Be careful , Using variables EXTRA_LIBS Collect any optional libraries , So that you can link to the executable later . Again , Variable EXTRA_INCLUDES For optional header files . When dealing with many optional components , This is a classic method , We will introduce modern methods in the next step .
Use libraries in source code
The corresponding changes to the source code are quite simple . First ,tutorial.cxx It includes MathFunctions.h The header file :
#ifdef USE_MYMATH
include "MathFunctions.h"
#endif
then , In the same file , Use USE_MYMATH Controls which square root function to use :
#ifdef USE_MYMATH
const double outputValue = mysqrt(inputValue);
#else
const double outputValue = sqrt(inputValue);
#endif
Because the source code now needs USE_MYMATH, We can add it to TutorialConfig.h.in:
#cmakedefine USE_MYMATH
Tests and exercises
Final Step2/CMakeLists.txt The contents are as follows
cmake_minimum_required(VERSION 3.10)
# set the project name and version
project(Tutorial VERSION 1.0)
# specify the C++ standard
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED True)
# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
# configure a header file to pass some of the CMake settings
# to the source code
configure_file(TutorialConfig.h.in TutorialConfig.h)
# add the MathFunctions library
if(USE_MYMATH)
add_subdirectory(MathFunctions)
list(APPEND EXTRA_LIBS MathFunctions)
list(APPEND EXTRA_INCLUDES "${PROJECT_SOURCE_DIR}/MathFunctions")
endif()
# add the executable
add_executable(Tutorial tutorial.cxx)
target_link_libraries(Tutorial PUBLIC ${EXTRA_LIBS})
# add the binary tree to the search path for include files
# so that we will find TutorialConfig.h
target_include_directories(Tutorial PUBLIC
"${PROJECT_BINARY_DIR}"
${EXTRA_INCLUDES}
)
tutorial.cxx The contents are as follows
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>
#include "tutorial_config.h"
#ifdef USE_MYMATH
#include "math_functions.h"
#endif
int main(int argc, char *argv[])
{
// if(argc<2){
// fprintf(stdout, "Uage: %s number\n", argv[0]);
// return 1;
// }
if (argc < 2)
{
// report version
std::cout << argv[0] << " Version " << Tutorial_VERSION_MAJOR << "."
<< Tutorial_VERSION_MINOR << std::endl;
std::cout << "Usage: " << argv[0] << " number" << std::endl;
return 1;
}
// double inputValue = atof(argv[1]);
const double inputValue = std::stod(argv[1]);
#ifdef USE_MYMATH
const double outputValue = mysqrt(inputValue);
#else
const double outputValue = sqrt(inputValue);
#endif
fprintf(stdout, "The square root of %g is %g\n", inputValue, outputValue);
return 0;
}
practice
1、Why is it important that we configure tutorial_config.h.in after the option for USE_MYMATH?
2、What would happen if we inverted the two?
function cmake Executable or cmake-gui To configure the project , Then build it using the build tool of your choice . Then run the built Tutorial Executable file .
test
Now let's update USE_MYMATH Value .
The simplest way is to use it in the terminal cmake-gui or ccmake.
You can also modify this option from the command line , as follows
cmake …/Step2 -DUSE_MYMATH=ON
cmake …/Step2 -DUSE_MYMATH=OFF
Rebuild and run this tutorial again .
Which function gives a better result ,sqrt still mysqrt?
边栏推荐
- 2022 information system management engineer examination outline
- Anaconda中配置PyTorch环境——win10系统(小白包会)
- Disabling and enabling inspections pycharm
- 普通程序员看代码,顶级程序员看趋势
- C # mixed graphics and text, written to the database in binary mode
- leetcode每日一练:旋转数组
- How to save the trained neural network model (pytorch version)
- VBA驱动SAP GUI实现办公自动化(二):判断元素是否存在
- Data access - entityframework integration
- Example tutorial of SQL deduplication
猜你喜欢
统计php程序运行时间及设置PHP最长运行时间
Mongodb (quick start) (I)
Check the WiFi password connected to your computer
基于YOLOv3的口罩佩戴检测
leetcode每日一练:旋转数组
Seven Devops practices to improve application performance
flask接口响应中的中文乱码(unicode)处理
查看自己电脑连接过的WiFi密码
Oracle recovery tools -- Oracle database recovery tool
2022新版PMP考试有哪些变化?
随机推荐
PMP认证需具备哪些条件啊?费用多少啊?
flask接口响应中的中文乱码(unicode)处理
Flask solves the problem of CORS err
Vulnerability recurrence - 48. Command injection in airflow DAG (cve-2020-11978)
Is it safe to open an account online? What is the general interest rate of securities financing?
解决“双击pdf文件,弹出”请安装evernote程序
Knowledge points of MySQL (6)
Disabling and enabling inspections pycharm
蚂蚁金服的暴富还未开始,Zoom的神话却仍在继续!
SQL Server(2)
Data access - entityframework integration
为什么阳历中平年二月是28天
QT console printout
Is it safe for China Galaxy Securities to open an account? How long can I buy stocks after opening an account
毫无章法系列
ICML 2022 | Meta提出鲁棒的多目标贝叶斯优化方法,有效应对输入噪声
C # realizes crystal report binding data and printing 3-qr code barcode
Kafaka技术第一课
7 pratiques devops pour améliorer la performance des applications
Cartoon: interesting pirate problem (full version)