[aclug-L] Re: c primer

[Tom Hull <thull@xxxxxxxxxxx>]

I'm not sure how to respond to this, but since this was the only response to
my C session proposal, maybe I should just throw a bit more fuel onto the fire.
(Ashes, whatever.)

My main point is that: if you want to learn to write non-trivial programs in
C, the most critical thing that you have to master is the type system, and
this is also the most difficult thing that you have to master. However, much
of what makes it difficult is that it is actually simpler (cruder, more
primitive) than you might expect. This simplicity also makes it possible
to do a presentation on it that might conceivably fit into a single night's
program. At least that's my opinion. I've never tried to put together such
a presentation, and I've never seen a book which presents this material in
a way that is as simple and clear as I think should be possible.

Now, the question of whether you want to learn C, or why you should want to
learn C, that's another question. And the other question you raise, how to
introduce beginners to programming, that's yet another question -- and one
that's not necessarily addressed through C.

Consider the following list:

 1) assembly language
 2) C
 3) C++
 4) Perl or Python
 5) shell (bash, ksh)

These are all general purpose programming languages, listed from the lowest
to the highest level. By level, the main thing we mean is how much work you
can do with a single command (higher level is more), and how much detail
control you have over that work (higher level is less).

Now, where you start in this hierarchy depends on what you want to do. I think
the two main reasons for anyone to start programming are empowerment (the
ability to get things done) and enlightenment (the ability to understand how
they work, and why). In general, if empowerment is more important, start with
a higher level language -- either general purpose or something specific to
what you're interested in, which could be SQL or some application-specific
scripting language. If enlightenment is more important, start with a lower
level language -- which probably means C. (Hardly anyone actually writes in
assembler anymore, and you're unlikely to run across it except in the lowest
level of machine-specific coding, or in debugging applications in very dire
straits [kernel, or no source code].)

jg wrote:
> 
> Hi...
> Well, I personally wouldn't know how many people in the group have
> "any" interest in this. I do know that learning C "first" would be a smart
> move for anyone wanting to learn any other modern computer language. If
> the topic of C programming were limited to a one night presentation and
> there is interest in C concepts, your plan sounds good. If there is no
> interest, than maybe a more beginner introduction would be better in order
> to introduce non-programmers. By "beginner, I mean talk about suggested
> books to buy/read.

If you want to learn to program, one of the best things you can do is to
read real programs. Nobody has managed to distill these into books (except
maybe Donald Knuth). The things that show up in books are illustrative
fragments, not real programs. Most of them are worthless.

> Discuss why the C language is important. How it
> differs from other languages. Why it is used more for UNIX than for
> Windows.

Not true. C is fundamental to Windows (although Microsoft has done some
hacky things to it). MFC is a C++ abstraction on top of the C WinAPI.
VB is a primitive widget-builder plus a bunch of sludge on top of C.

> Also discuss the relationship between C, C++ & Java.

C is mostly good for implementing simple procedures, but you have to be
very conscious of and conscientious about memory. C++ handles some (not
all) of the memory issues for you. It also lets you think in terms of
higher level constructs, like objects, classes, frameworks, patterns.
This is great if you're merely a user of these things, but can require
a lot more thinking to design them reasonably well.

Java always struck me as a solution in search of a problem. I've never
found the problem, so have no idea what it's good for. It is, superficially,
a simpler and cleaner object-oriented language than C++.

> Also, how much does C have in common with Perl, Python & TCL.

Nothing important. What's important in C is the type system, the memory
model, function calls, and the scoping associated with them. HLL's bury
all of that. (There are, of course, generic programming concepts that
almost all languages share, and some common function names -- Perl in
particular has built-in functions which map fairly closely to the Unix
API.)

Think of it this way: for every line of TCL that you write, something
like 50 lines of C get executed. The good news is that you didn't have
to write those 50 lines; the bad news is that you don't really know
what they do, whereas if you had written them you would know what they
do. As long as TCL works, that's probably a good tradeoff, but when it
doesn't work, someone's gotta dig into the C. The guy who wrote TCL
wrote it in C. (Same for Perl and Python.)

> Perhaps a presentation
> on "Introduction to Programming" would be better (with the discution
> revolving around C).

I think "Introduction to Programming" should start with a higher level
language, so you can do something quickly rather than drown in details.
TCL/TK might be good for that.

> On a different (2nd) night, a presentation on "The
> Concepts of C" (like proposed in your e-mail, below).
> 
> This weekend, I researched the books that are available for C.
> I came up with a list of three of the best tutorials:
> 1. "C Programming: A Modern Approach"
> 2. "Pointers on C"

I haven't seen these books. From amazon.com, they look big and expensive.
I can't imagine writing 600 pages on C.

> 3. "The C Programming Language, 2nd Edition"

There's also a companion "C Answer Book", which provides solutions for
all of the exercises. The two books can be quite effective together.

> Best Reference:
> 1. "C: A Reference Manual"
> Best Style Book:
> 1. "The Practice of Programming"

My favorite C book is Donald Alcock's "Illustrating C". It's 214 pages
long, and designed like a comic book. The pictures help, and the code
samples are non-trivial. It also works as a reference. It's also out-
of-print.

BTW, throw away any C book which uses scanf() in the first 25% of the
book.

> One night cannot teach C, just like C in 21 hours can't be done.

I'd think one could do a complete survey course on C in 21 hours.
Your mileage as a student may vary, but everything could be covered,
and most people should be able to learn most of it. It's really not
that complex or difficult.

> But, we
> are a group of volunteers trying to help each other. The most we can do is
> help point ourselves in the right direction (even though the concept
> of the word "right" has become politically incorrect).
> 
> James G.
> 
> On Wed, 25 Oct 2000, Tom Hull wrote:
> 
> > At the last ACLUG meeting, James G. asked for someone to do a presentation
> > on the C programming language. The general reaction seemed to be: not in one
> > night. I've been thinking about this, and I think I could throw together
> > something on a limited subset of C, specifically:
> >
> >   -- object types and their memory representation
> >   -- type descriptors
> >   -- casts
> >   -- rvalues and lvalues
> >   -- array and pointer operations
> >   -- simple (non-bitfield) structures and unions
> >
> 
> > My question is, would this be of sufficient general interest?

-- 
/*
 *  Tom Hull * thull@xxxxxxxxxxx * http://www.ocston.org/~thull/
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