build.sh

mkdir build
pushd build
cmake ..
cmake --build .
popd

CMakeLists.txt

cmake_minimum_required(VERSION 3.15) # Define the minimum CMake version, can go lower
project(helloworld)                  # Your project name

add_executable(${PROJECT_NAME})      # Define an executable target, same name as project

target_sources(${PROJECT_NAME}       # Modern way of adding sources, add it to the executable named above
        PRIVATE                      # All "internal" code which will not be used by other external programs
        main.cpp)                    # The actual file list

main.cpp

#include <iostream>

int main(int argc, char* argv[]) {
        std::cout << "Hello World" << std::endl;
        return 0;
}