Update README and add test_your_setup folder

README.md

-# Programming in C++ 2025
+# Programming in C++ (2025)
 
+Course material for the course "Programming in C++", 19 -- 23 May 2025,
+organized by the Juelich Supercomputing Centre,
+Forschungszentrum Juelich, Germany.
 
 
-## Getting started
+# cxx2025
 
-To make it easy for you to get started with GitLab, here's a list of recommended next steps.
+You will need to pull from this repository periodically during this course.
 
-Already a pro? Just edit this README.md and make it your own. Want to make it easy? [Use the template at the bottom](#editing-this-readme)!
+If your computer does not have "git", you will need to use the download
+button to the left of the "Clone" button in the gitlab page.
 
-## Add your files
+## Recommended way of working with this material
 
-- [ ] [Create](https://docs.gitlab.com/ee/user/project/repository/web_editor.html#create-a-file) or [upload](https://docs.gitlab.com/ee/user/project/repository/web_editor.html#upload-a-file) files
-- [ ] [Add files using the command line](https://docs.gitlab.com/topics/git/add_files/#add-files-to-a-git-repository) or push an existing Git repository with the following command:
+The downloaded or cloned material from this repository will be updated
+during the course days. You should keep one copy of the examples and
+exercises in the pristine form, and work on your own duplicates.
+For example, to work on the examples in chapter 1,
+do as follows:
 
+```bash
+    cd chapter1
+    cp -r examples mine
+    cd mine
+    g++ -std=c++23 math_functions.cc
+    ./a.out
 ```
-cd existing_repo
-git remote add origin https://gitlab.jsc.fz-juelich.de/sdlbio-courses/programming-in-cxx-2025.git
-git branch -M main
-git push -uf origin main
-```
-
-## Integrate with your tools
-
-- [ ] [Set up project integrations](https://gitlab.jsc.fz-juelich.de/sdlbio-courses/programming-in-cxx-2025/-/settings/integrations)
-
-## Collaborate with your team
-
-- [ ] [Invite team members and collaborators](https://docs.gitlab.com/ee/user/project/members/)
-- [ ] [Create a new merge request](https://docs.gitlab.com/ee/user/project/merge_requests/creating_merge_requests.html)
-- [ ] [Automatically close issues from merge requests](https://docs.gitlab.com/ee/user/project/issues/managing_issues.html#closing-issues-automatically)
-- [ ] [Enable merge request approvals](https://docs.gitlab.com/ee/user/project/merge_requests/approvals/)
-- [ ] [Set auto-merge](https://docs.gitlab.com/user/project/merge_requests/auto_merge/)
-
-## Test and Deploy
-
-Use the built-in continuous integration in GitLab.
-
-- [ ] [Get started with GitLab CI/CD](https://docs.gitlab.com/ee/ci/quick_start/)
-- [ ] [Analyze your code for known vulnerabilities with Static Application Security Testing (SAST)](https://docs.gitlab.com/ee/user/application_security/sast/)
-- [ ] [Deploy to Kubernetes, Amazon EC2, or Amazon ECS using Auto Deploy](https://docs.gitlab.com/ee/topics/autodevops/requirements.html)
-- [ ] [Use pull-based deployments for improved Kubernetes management](https://docs.gitlab.com/ee/user/clusters/agent/)
-- [ ] [Set up protected environments](https://docs.gitlab.com/ee/ci/environments/protected_environments.html)
-
-***
-
-# Editing this README
-
-When you're ready to make this README your own, just edit this file and use the handy template below (or feel free to structure it however you want - this is just a starting point!). Thanks to [makeareadme.com](https://www.makeareadme.com/) for this template.
-
-## Suggestions for a good README
-
-Every project is different, so consider which of these sections apply to yours. The sections used in the template are suggestions for most open source projects. Also keep in mind that while a README can be too long and detailed, too long is better than too short. If you think your README is too long, consider utilizing another form of documentation rather than cutting out information.
 
-## Name
-Choose a self-explaining name for your project.
-
-## Description
-Let people know what your project can do specifically. Provide context and add a link to any reference visitors might be unfamiliar with. A list of Features or a Background subsection can also be added here. If there are alternatives to your project, this is a good place to list differentiating factors.
-
-## Badges
-On some READMEs, you may see small images that convey metadata, such as whether or not all the tests are passing for the project. You can use Shields to add some to your README. Many services also have instructions for adding a badge.
-
-## Visuals
-Depending on what you are making, it can be a good idea to include screenshots or even a video (you'll frequently see GIFs rather than actual videos). Tools like ttygif can help, but check out Asciinema for a more sophisticated method.
-
-## Installation
-Within a particular ecosystem, there may be a common way of installing things, such as using Yarn, NuGet, or Homebrew. However, consider the possibility that whoever is reading your README is a novice and would like more guidance. Listing specific steps helps remove ambiguity and gets people to using your project as quickly as possible. If it only runs in a specific context like a particular programming language version or operating system or has dependencies that have to be installed manually, also add a Requirements subsection.
-
-## Usage
-Use examples liberally, and show the expected output if you can. It's helpful to have inline the smallest example of usage that you can demonstrate, while providing links to more sophisticated examples if they are too long to reasonably include in the README.
-
-## Support
-Tell people where they can go to for help. It can be any combination of an issue tracker, a chat room, an email address, etc.
-
-## Roadmap
-If you have ideas for releases in the future, it is a good idea to list them in the README.
-
-## Contributing
-State if you are open to contributions and what your requirements are for accepting them.
-
-For people who want to make changes to your project, it's helpful to have some documentation on how to get started. Perhaps there is a script that they should run or some environment variables that they need to set. Make these steps explicit. These instructions could also be useful to your future self.
+Only examples (which includes some exercises) and solutions need to
+be duplicated. You don't need to clone the entire material as that
+includes the PDFs of the book, course slides and other utillities.
+
+
+## Testing your set up
+
+To work with this material, you will need to have a fairly up-to-date
+C++ compiler. GCC version 15.1 or Clang version 19.1 is recommended.
+These will be available for you in the course room.
+Microsoft's Visual C++ compiler has excellent support for C++23, if
+you have the latest version installed. During the course, we will focus
+on using open source tools, which are available to everyone, rather
+than proprietary tools.
+
+To test your setup, proceed as follows:
+
+```bash
+    cd wherever_you_downloaded_or_cloned_this_thing
+    cd test_your_setup
+    g++ hello.cc -o hello.gcc
+    ./hello.gcc
+    clang++ hello.cc -o hello.clang
+    ./hello.clang
+    g++ -std=c++23 hello_c++23.cc -o hello_cxx23.gcc
+    ./hello_cxx23.gcc
+    clang++ -std=c++23 hello_c++23.cc -o hello_cxx23.clang
+    ./hello_cxx23.clang
+```
 
-You can also document commands to lint the code or run tests. These steps help to ensure high code quality and reduce the likelihood that the changes inadvertently break something. Having instructions for running tests is especially helpful if it requires external setup, such as starting a Selenium server for testing in a browser.
+# Using aliases to save some typing
+
+As the above examples show, we will often need to type a
+lot of options to compile our programs during this course,
+since we want to use C++23, which is not the default
+standard for the compilers yet. A few convenient aliases
+have been prepared which you can use to shorten the
+above compilation steps. These aliases are available as
+soon as you log in to your account in the course room.
+Example use, for clang is as follows. To use gcc instead,
+replace C with G.
+
+```bash 
+C hello.cc 
+C hello_c++23.cc 
+```
 
-## Authors and acknowledgment
-Show your appreciation to those who have contributed to the project.
+In case you wish to use them on another system, for instance,
+on your own laptop, do as follows:
 
-## License
-For open source projects, say how it is licensed.
+```bash
+source course_material_dir/code/bash/aliases.sh
+```
 
-## Project status
-If you have run out of energy or time for your project, put a note at the top of the README saying that development has slowed down or stopped completely. Someone may choose to fork your project or volunteer to step in as a maintainer or owner, allowing your project to keep going. You can also make an explicit request for maintainers.

test_your_setup/README.md

+# Compile:
+
+## hello.cc
+g++ hello.cc
+clang++ hello.cc
+
+## hello_c++23.cc
+g++ -std=c++23 hello_c++23.cc 
+clang++ -std=c++23 -stdlib=libc++ hello_c++23.cc 
+
+## hello_m.cc
+
+With gcc:
+g++ -std=c++23 -fmodules -xc++-system-header print
+g++ -std=c++23 -fmodules hello_m.cc
+Note: For GCC versions before 15, replace -fmodules by -fmodules-ts
+
+with clang:
+clang++ -std=c++23 -stdlib=libc++ -fmodules hello_m.cc
+
+## hello_c++23_m.cc
+
+With gcc:
+g++ -std=c++23 -fmodules -xc++-system-header concepts
+g++ -std=c++23 -fmodules -xc++-system-header iostream
+g++ -std=c++23 -fmodules hello_c++23_m.cc
+
+With clang:
+clang++ -std=c++23 -stdlib=libc++ -fmodules hello_c++23_m.cc
+
+

test_your_setup/hello.cc

+#include <iostream>
+
+auto main() -> int
+{
+    std::cout << "Hello, world!\n";
+}

test_your_setup/hello_c++23.cc

+#include <print>
+#include <concepts>
+
+auto message(auto&& x)
+{
+    std::print("{}\n", x);
+}
+
+template <class T>
+concept is_a_number = std::integral<T> or std::floating_point<T>;
+
+auto main() -> int
+{
+    message("Hello, world!");
+    auto n = 1234.0;
+    if constexpr (is_a_number<decltype(n)>)
+	std::print("{} is a number.\n", n);
+    else
+	std::print("{} is not a number!\n", n);
+}
+

test_your_setup/hello_c++23_m.cc

+import <print>;
+import <concepts>;
+
+void message(auto&& x)
+{
+    std::print("{}\n", x);
+}
+
+template <class T>
+concept is_a_number = std::integral<T> or std::floating_point<T>;
+
+auto main() -> int
+{
+    message("Hello, world!");
+    auto n = 1234.0;
+    if constexpr (is_a_number<decltype(n)>)
+	std::print("{} is a number.\n", n);
+    else
+	std::print("{} is not a number!\n", n);
+}
+

test_your_setup/hello_m.cc

+import <iostream>;
+
+auto main() -> int
+{
+    std::cout << "Hello, world!\n";
+}
+