Cmake learning notes (1) compile single source programs with cmake

This is what I'm learning to use CMake Notes taken when , Main reference 《CMake Cookbook》 This book .

use CMake Compile single source program , The example program is as follows ：

#include <cstdlib>
#include <iostream>
#include <string>

std::string say_hello() {
     return std::string("Hello, CMake world!"); }

int main() {
    
  std::cout << say_hello() << std::endl;
  return EXIT_SUCCESS;
}

CMakeLists.txt as follows ：

# CMake  Version for 
cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
#  Declare the project name and language 
project(recipe-01 LANGUAGES CXX)
#  To guide the CMake Create target program 
add_executable(hello-world hello-world.cpp)

Build command ：

mkdir -p build
cd build
cmake ..
#  The above three items are equivalent to  cmake -H. -Bbuild
cmake --build .

cmake -H. -Bbuild Medium -H. Means to find in the current folder CMakeList.txt file ,-Bbuild It means in build Folder to generate files needed for compilation . The command is still in standardization, so it is more recommended to use the traditional way .

In the created build There are the following files under the folder ：

• Makefile： To guide the make Build the configuration file of the project .
• CMakeFiles： Storage of temporary documents ,CMake Detecting the operating system 、 Temporary files generated when the compiler waits . besides , According to the selected generator （ stay Unix Class system is Unix Makefiles generator, stay Windows The default is Visual Studio） Different , It will also include project related files .
• cmake_install.cmake： Contains installation rules CMake Script , Use during installation .
• CMakeCache.txt：CMake cache

cmake --build . Is a cross platform command , Will call the platform's native build commands , stay linux Call in make.

Build options

In this example, the only construction goal is hello-world This executable file , But in fact cmake Support more build options . Run the command cmake --build . --target help You can see the available build items ：

$ cmake --build . --target help
The following are some of the valid targets for this Makefile:
... all (the default if no target is provided)
... clean
... depend
... rebuild_cache
... hello-world
... edit_cache
... hello-world.o
... hello-world.i
... hello-world.s

These build options are available through cmake --build . --target <target-name> Generate .

• all （ stay VS Generator is ALL_BUILD） Is the default build option , All goals in the project will be built
• clean Clear all generated files
• depend call CMake Generate dependencies for source code
• rebuild_cache call CMake The reconstruction CMakeCache.txt. This is needed when adding new entries to the source .
• edit_cache Allow direct editing of cache entries

For more complex projects with testing links and installation rules ,CMake The following additional build options are generated

• test （ stay VS Generator is RUN_TESTS） Will be in CTest Run the test sample with the support of
• install Run the installation rules of the project .
• package call CPack Generate a redistributable package for the project .

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