Create a singly-linked list from scratch in C without having memory leaks
Final results
The trials are done, and the results are in. See the REPORT_VALGRIND.md file for all the details, and my conclusions.
Background
On the Computer Science Educators of the Stack Exchange Network a question was posed: "Why are pointers a key topic in a CS curriculum and oft cited as something people don't get?". User ncmathsadist posted an answer indicating the difficulty with pointers in C is the memory management associated with their use rather than their actual usage.
In connection with that answer, and by way of demonstrating the difficulty of memory management, the user issued a challenge, so to speak:
Try coding a singly-linked list from scratch in C without having memory leaks.
Furthermore, the user made the statement that
It is an edifying and humility-instilling experience.
The user closed their post with a final warning:
Warning: valgrind will hurt your feelings.
Explaining the repo's usage pattern
Since I have never written any code in C, including the infamous Hello World program, I thought I would make a good test subject for that challenge.
This repository will likely have an unusually high number of commits, since I intend to document the developement process, and my learning, rather than only committing "working code" as is the normal practice for git repositories.
Of course, I've never use valgrind either, so that will have to be installed, and learned, after I "think" I have the solution in hand. Testing for memory leaks with valgrind beforehand might be considered cheating in this case, so I'll withhold its installation and use until I have my "final answer, Alex."
System in use for development and testing
CPU:
AMD FX™-8300 Eight-Core Processor
Memory:
16,818,520,064 bytes
uname -a:
Linux SuSE 4.4.143-65-default #1 SMP Tue Aug 14 09:18:29 UTC 2018 (4e090cc) x86_64 x86_64 x86_64 GNU/Linux`
gcc --version:
gcc (SUSE Linux) 4.8.5 Copyright (C) 2015 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Valgrind Info (Installed 2016-08-31 03:54:04 UTC)
Current version of Valgrind is Valgrind 3.13.0 - 14 June 2017.
Available from http://valgrind.org/downloads/current.html.
Includes a sepecial warning:
Programs running under Valgrind run significantly more slowly, and use much more memory -- e.g. more than twice as much as normal under the Memcheck tool. Therefore, it's best to use Valgrind on the most capable machine you can get your hands on.
$ valgrind --version
yields
valgrind-3.13.0
Looks like all is well.
$ valgrind --leak-check=full ls -l
yields
==17534==
==17534== HEAP SUMMARY:
==17534== in use at exit: 20,507 bytes in 34 blocks
==17534== total heap usage: 633 allocs, 599 frees, 96,021 bytes allocated
==17534==
==17534== LEAK SUMMARY:
==17534== definitely lost: 0 bytes in 0 blocks
==17534== indirectly lost: 0 bytes in 0 blocks
==17534== possibly lost: 0 bytes in 0 blocks
==17534== still reachable: 20,507 bytes in 34 blocks
==17534== suppressed: 0 bytes in 0 blocks
==17534== Reachable blocks (those to which a pointer was found) are not shown.
==17534== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==17534==
==17534== For counts of detected and suppressed errors, rerun with: -v
==17534== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
That looks to me like it's a "done deal" for the install of Valgrind.
License and copyright
This software is available under the MIT License.
Copyright ©2018 Gypsy Spellwaver
The MIT License
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obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without restriction,
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publish, distribute, sublicense, and/or sell copies of the Software,
and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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