Giters

cemserit / eRCaGuy_hello_world

"hello world" demos & templates for various languages, incl. gcc build commands for C & C++

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool

eRCaGuy_hello_world

"hello world" demos & templates for various languages, incl. gcc build commands for C & C++

See also my eRCaGuy_hello_world_data project.

By Gabriel Staples
www.ElectricRCAircraftGuy.com

Status:

  1. Many solid C & C++ demos are done and work!
  2. A Python demo also is in place to show how to parse a YAML file.

See the tree output below to see the file/folder structure.

For beginners and experts alike: not your average "hello world" examples

Note that these are NOT just your standard "simple" hello world demos for absolute beginners. Rather, they are simple enough for beginners but also contain some advanced techniques and tips & tricks to act as good reminders or teaching for more expert programmers too. I, myself, regularly reference my own examples here to remind myself of some of these details which are easy to forget. There's no sense stressing about trying to remember everything. Instead of trying to remember everything, just remember where to look (here in this case).

Examples of more advanced principles taught herein:

1. C and C++:

  1. How to generate intermediate build files, including .ii, .s, and .o.
    1. See "cpp/hello_world.cpp"
  2. How to make a single file compile in both C and C++ by using the #ifdef __cplusplus extern "C" { brace trick
    1. See "c/hello_world.c"
  3. How to use a forward declaration of printf rather than including stdio.h to make it link
    1. See "c/hello_world.c"
  4. How to do cross-platform sleep in Windows or Linux
    1. See "c/hello_world_sleep.c"
  5. A reminder to use -Wall -Werror for better code safety and quality
    1. See "c/hello_world.c"
  6. How to use g3 for full debugging info
    1. See "c/hello_world.c" and
    2. "c/hello_world_sleep.c"
  7. How to specify the C or C++ version you are compiling for, such as c90, c99, or c11 (C 2011), or c++98, c++03 (C++ 2003), or c++11 (C++ 2011)
    1. See "c/hello_world.c" and
    2. "c/hello_world_sleep.c"
  8. How to pass entire functions or curly-brace-scoped { } code blocks, as though they were a single parameter, into a macro to be evaluated
    1. See "cpp/macro_practice/advanced_macro_usage_pass_in_entire_func.cpp"
  9. How to do integer rounding UP, DOWN, and to NEAREST whole integer during division using 3 different techniques: 1) macros, 2) gcc/clang statement expressions, and 3) C++ function templates. This also is a great unit test example using simple hand-written unit tests.
    1. See "c/rounding_integer_division/" directory
    2. If you'd like to see how to use googletest (gtest) and googlemock (gmock) instead of writing custom unit tests, see my other project here instead: https://github.com/ElectricRCAircraftGuy/eRCaGuy_gtest_practice. It also acts as a good demo of how to get up and running quickly with Google's Bazel build system.
  10. Witness that the C++ std::unordered_map<T_key, T_value> unordered map (hash table) class automatically implicitly creates a new key/value pair each time you attempt to read OR write to a value (or any members of a complex value, such as a struct or class) which belongs to a non-existing key! In other words, reading or writing any key/value which does NOT yet exists causes std::unordered_map<> to automatically, dynamically, generate it right on the spot for you to access it! This is confusing behavior at first, as it happens implicitly behind the scenes, so it needs to be understood. Once understood, it is a powerful feature to use, but a one or two-line comment to exlain that you intend dynamic allocation to happen, above any lines in production code where you use this, would be wise.
    1. See "cpp/unordered_map_practice/unordered_map_hash_table_implicit_key_construction_test.cpp"
  11. Case-insensitive strncmp() function, with unit tests.
    1. See "c/onlinegdb--strncmpci.c"
  12. Example of how to manually write unit tests.
    1. See "c/onlinegdb--strncmpci.c"
    2. Note: for Google Test (gtest/gmock) examples, including how to use the Bazel build system, see my repo here instead: https://github.com/ElectricRCAircraftGuy/eRCaGuy_gtest_practice.
  13. How to use a const reference to a vector, with a default parameter, as an input param to a function!
    1. See "cpp/onlinegdb--const_reference_to_vector__default_func_parameter.cpp"

Additional C and C++ build notes (ex: w/gcc or clang compilers):

  1. Use -Wwarning-name to turn ON build warning "warning-name", and -Wno-warning-name to turn OFF build warning "warning-name". -W turns a warning ON, and -Wno- turns a warning OFF. Here's what gcc has to say about it (source: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html; emphasis added):

    You can request many specific warnings with options beginning with -W, for example -Wimplicit to request warnings on implicit declarations. Each of these specific warning options also has a negative form beginning -Wno- to turn off warnings; for example, -Wno-implicit. This manual lists only one of the two forms, whichever is not the default.

  2. Instead of -g3, use -ggdb to build debug information specifically for the GNU gdb debugger. If using the clang (LLVM) compiler instead of gcc, you may also use -glldb to build debug information specifically for the clang LLDB debugger. Note that if you use -glldb, it usually builds debug symbols and information which works just fine with gdb too, so you can generally use either debugger with the same built symbols in that case.

  3. Use -Wall -Wextra -Werror (which is a good idea) to see all warnings and to convert all warnings to errors, to make you write better code. Some people may leave off -Wextra, and just use -Wall -Werror. Others may also like to add -Wpedantic to that list (now it's -Wall -Wextra -Wpedantic -Werror) to enforce ISO C and ISO C++ standards, but other people or code-bases will explicitly turn OFF pedantic with -Wno-pedantic to explicitly DISABLE pedantic (ISO standards) checks and ALLOW compiler extensions. Personally, I prefer to leave compiler extensions ENABLED (meaning: do NOT use -Wpedantic), as compiler extensions are very frequently used and very useful, especially in small, embedded, low-level and hardware-centric systems such as microcontrollers.

    • In other words, I recommend that you DO use -Wall -Wextra -Werror but that you NOT use -Wpedantic, but if you'd like to use -Wpedantic as well, you may. See just below for additional details.
    • For details on which warning flags -Wall and -Wextra each turn on, refer to the gcc user manual here (https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html), and search the page for these warnings, or just scroll partway down. There's a nice list detailing what individual warning flags are under each (-Wall, and -Wextra).

  4. Add the -Wpedantic or -pedantic (same thing) build flag to enforce strict ISO C or ISO C++ standards and "reject all programs that use forbidden extensions". Or, conversely, add -Wno-pedantic to ENABLE extensions and turn a previously-set -Wpedantic back OFF. -Wpedantic NOT being on is the default. See gcc's user manual section on Warning Options, for example, as well as the bullet just above, for details: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html.

    • Some people want strict ISO C and C++ functionality only. They use -Wpedantic.
    • Some libraries REQUIRE compiler extensions and explicitly have -Wno-pedantic set for the library to enable compiler extensions and disable any previously-set -Wpedantic flags. Sometimes this is just for certain files which require exceptions to use certain compiler extensions.
    • Others rely on compiler extensions and do NOT use -Wpedantic. I am in this latter category and prefer NOT to use -Wpedantic, so that I CAN use gcc (or clang) compiler extensions. They are good. They are safe. They are helpful. They just may not be quite as portable across compilers is all, though from gcc to clang and back again, you are usually ok to use them, since clang strives to be gcc-compatible by design (see http://clang.llvm.org/: clang strives to be gcc compatible: "End-User Features" they advertise include: "GCC compatibility").
    • See also my notes about -Wpedantic in the previous higher-level bullet just above this one.

  5. clang, but NOT gcc, also has a -Weverything option which appears to include things such as -Wpedantic. You can test it here: https://godbolt.org/z/qcYKd1. Notice the -Wvla-extension warning we get since we are relying on a C99 extension in C++ in this case, and we have -Weverything set. We get the same warning if we just use -Wpedantic, as shown here: https://godbolt.org/z/M9ahE4, indicating that -Weverything does in fact include -Wpedantic. We get no warning if we have neither of those flags set: https://godbolt.org/z/j8sfsY. Despite -Weverything existing and working in clang, however, I can find no documentation whatsoever on its existence, neither in the clang man pages nor in the online manual here: https://clang.llvm.org/docs/DiagnosticsReference.html.

2. Python:

  1. How to create, parse, and print YAML files. How to find the directory path a called Python file is in.
    1. See "python/yaml_import/import_yaml_test.py" and other files in that directory.

3. markdown:

  1. github_readme_center_and_align_images.md: show how to insert and center, align left, align right, etc. images in GitHub readmes in markdown. Ex: resize this image to 15% auto-resizing width, and:

Align left:

Align center:

Align right:

6 images in a row:

File Structure:

(Output of tree)

$ tree
.
├── arduino
│   └── todo.txt
├── awk
│   ├── awk_hello_world_SAMPLE_OUTPUT.txt
│   ├── awk_hello_world.sh
│   ├── awk_syntax_tests.sh
│   └── input_file_1.txt
├── bash
│   ├── Link to ElectricRCAircraftGuy--PDF2SearchablePDF [THIS IS A SOLID BASH EXAMPLE!].desktop
│   ├── Link to PDF2SearchablePDF--pdf2searchablepdf.sh at master · ElectricRCAircraftGuy--PDF2SearchablePDF.desktop
│   └── todo.txt
├── c
│   ├── c - Where do we use .i files and how do we generate them? - Stack Overflow.desktop
│   ├── hello_world
│   ├── hello_world.c
│   ├── hello_world_sleep
│   ├── hello_world_sleep.c
│   ├── Link to c - Prototype of printf and implementation - Stack Overflow%%%%%+ [MY OWN ANS!].desktop
│   ├── Link to c - Where do we use .i files and how do we generate them - Stack Overflow%%%%% [MY OWN ANS!].desktop
│   ├── Link to Using the GNU Compiler Collection (GCC): Warning Options%%%%% [always use `-Wall -Werror`!].desktop
│   ├── rounding_integer_division
│   │   ├── c - Rounding integer division (instead of truncating) - Stack Overflow.desktop
│   │   ├── readme.md
│   │   ├── rounding_integer_division.c -> rounding_integer_division.cpp
│   │   ├── rounding_integer_division.cpp
│   │   ├── rounding_integer_division.md
│   │   ├── run_tests_sample_output.txt
│   │   └── run_tests.sh
│   └── Using the GNU Compiler Collection (GCC): Warning Options-1.desktop
├── cpp
│   ├── bin
│   │   ├── struct_initialization
│   │   ├── struct_initialization.i
│   │   ├── struct_initialization.ii
│   │   ├── struct_initialization.o
│   │   └── struct_initialization.s
│   ├── bin_hello_world
│   │   ├── hello_world
│   │   ├── hello_world.ii
│   │   ├── hello_world.o
│   │   └── hello_world.s
│   ├── hello_world.cpp
│   ├── Link to c - Where do we use .i files and how do we generate them - Stack Overflow%%%%% [MY OWN ANS!].desktop
│   ├── Link to How to initialize a struct to 0 in C++ - Stack Overflow%%%%%+ [my own Q & A].desktop
│   ├── Link to Why doesn't initializing a C++ struct to `= {0}` set all of its members to 0? - Stack Overflow%%%%%++ [my own Q; very good answers here!].desktop
│   ├── macro_practice
│   │   ├── advanced_macro_usage_pass_in_entire_func.cpp
│   │   └── bin_adv_macro
│   │       ├── advanced_macro_usage_pass_in_entire_func
│   │       ├── advanced_macro_usage_pass_in_entire_func.ii
│   │       ├── advanced_macro_usage_pass_in_entire_func.o
│   │       └── advanced_macro_usage_pass_in_entire_func.s
│   ├── run_hello_world.sh
│   ├── run_struct_initialization.sh
│   ├── struct_initialization.c -> struct_initialization.cpp
│   ├── struct_initialization.cpp
│   ├── template_practice
│   │   ├── explicit_template_specialization.cpp
│   │   ├── research
│   │   │   ├── (7) Template Specialization In C++ - YouTube.desktop
│   │   │   ├── Buckys C++ Programming Tutorials - 61 - Template Specializations - YouTube.desktop
│   │   │   ├── Link to explicit (full) template specialization - cppreference.com%%%%%+.desktop
│   │   │   ├── Link to template c++ - Google Search%%%%%.desktop
│   │   │   ├── Link to template specialization - Google Search%%%%%.desktop
│   │   │   ├── Link to template specialization - Google Search [videos]%%%%%.desktop
│   │   │   ├── partial template specialization - cppreference.com.desktop
│   │   │   ├── Template (C++) - Wikipedia.desktop
│   │   │   ├── Template (C++) - Wikipedia_GS_edit.pdf
│   │   │   └── Template (C++) - Wikipedia.pdf
│   │   └── run_explicit_template_specialization.sh
│   └── unordered_map_practice
│       ├── Link to GDB online Debugger - Code, Compile, Run, Debug online C, C++ [unordered_map practice].desktop
│       ├── unordered_map_hash_table_implicit_key_construction_test
│       └── unordered_map_hash_table_implicit_key_construction_test.cpp
├── eRCaGuy_hello_world--what to work on next--Gabriel.odt
├── java
│   └── todo.txt
├── LICENSE
├── python
│   └── yaml_import
│       ├── import_yaml_test.py
│       ├── my_config1.yaml
│       └── my_config2.yaml
└── README.md

16 directories, 68 files

Changelog

INITIAL DEVELOPMENT PHASE:

  • Use version numbers 0.MINOR.PATCH for the initial development phase; ex: 0.1.0, 0.2.0, etc.
  • Increment just the MINOR version number for each new 0.y.z development phase enhancement, until the project is mature enough that you choose to move to a 1.0.0 release
  • You may increment the PATCH number for bug fixes to your development code, or just increment the MINOR version number if there are also enhancements

MORE MATURE PHASE:

  • As the project matures, release a 1.0.0 version
  • Once you release a 1.0.0 version, do the following (copied from semver.org):
  • Given a version number MAJOR.MINOR.PATCH, increment the:
  1. MAJOR version when you make incompatible API changes,
  2. MINOR version when you add functionality in a backwards compatible manner, and
  3. PATCH version when you make backwards compatible bug fixes.

[v0.3.0] - 2020-05-23

  • Added "awk" folder with two sample programs: "awk_hello_world.sh" and "awk_syntax_tests.sh"

[v0.2.0] - 2020-04-18

  • Added "cpp/unordered_map_practice/unordered_map_hash_table_implicit_key_construction_test.cpp"

[v0.1.0] - 2020-04-14

  • Added changelog and started tracking a "version" number via the changelog
  • Added "python/yaml_import/import_yaml_test.py" and related .yaml configuration files to demonstrate importing and using YAML configuration files in Python
  • A bunch of really good C and C++ examples were already in place at this time, as I had been doing this project for quite some time without a Changelog

About

"hello world" demos & templates for various languages, incl. gcc build commands for C & C++

License:MIT License

Languages

Language:Assembly 79.7%Language:C++ 12.8%Language:C 3.7%Language:Shell 2.6%Language:Python 1.2%