Video summary
In this discussion, Brian Kernighan reflects on the enduring legacy of C and his co-authored book, *The C Programming Language*, which he considers one of the most impactful works in programming history. He attributes the language's longevity to its unique combination of expressiveness and efficiency, allowing developers to write naturally while maintaining high performance even with the limited computational power available fifty years ago. Kernighan highlights that C found a perfect synergy within the Unix environment; because both the operating system and essential tools were written in C, programs developed on one machine could easily be ported to others running Unix. This created a positive feedback loop where the language's utility reinforced its adoption across dozens of systems, cementing its status as a foundational technology that has survived nearly five decades of Moore's Law advancements. The creation of what became known as "the definitive book" on C was not part of an initial grand plan but rather an accident of timing and circumstance when Kernighan and Dennis Ritchie began working in 1977. At that time, Unix systems were spreading rapidly across dozens to hundreds of computers, yet there were no other books available; Bell Labs remained the sole source for information on C. Recognizing that Dennis Ritchie was an authoritative figure who had already written a superb reference manual, Kernighan persuaded him to expand into a full book. The resulting text benefited from Ritchie's exceptional writing style and crystal-clear prose regarding syntax, while Kernighan focused heavily on crafting expository material and selecting examples. They worked collaboratively through a process of refining ideas back and forth, ensuring the content was both educational and practical for readers learning the language at that specific moment in its evolution. Kernighan emphasizes that the power of good programming lies in using representative examples rather than isolated syntax exercises. He notes that many modern books fail by presenting trivial tasks like adding three numbers without explaining how to acquire or format those inputs, whereas their approach focused on realistic text processing problems typical of Unix environments. The book featured simple yet meaningful projects such as copying input and outputting it again, similar to the `cat` command, or reading data and transforming it before writing results out, akin to a `grep` operation. These examples were chosen because they represented fundamental tasks programmers actually wanted to accomplish, allowing readers to understand core concepts while seeing how code could be modified for their own specific needs. Ultimately, Kernighan argues that the true value of these examples is providing something directly useful or highly representative of real-world utility within a vein of text processing—reading input, manipulating it, and writing output. He admits that no book can be perfect in its attempt to cover every scenario, but their goal was consistently to demonstrate how to do things that felt genuinely helpful rather than purely theoretical. By grounding the learning experience in practical applications like reading files or formatting data neatly, they aimed to show programmers not just *how* to write code, but why it matters and what problems such code could solve. This philosophy of teaching through realistic, useful examples helped establish a standard for how C should be taught and applied, influencing generations of developers who continue to rely on the language today.
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so what's to use
you wrote a book c programming language
what and c
is probably one of the most important
languages in the history of programming
languages
if if you kind of look at impact what do
you think is the most elegant
or powerful part of c
why did it survive why did it have such
a long lasting impact
i think it found a sweet spot that in
of expressiveness so you could really
write things in a pretty natural way
and efficiency which was particularly
important when computers were
not nearly as powerful as they are today
you can put yourself back
50 years almost in terms of what
computers could do and that's you know
roughly four or five generations decades
of moore's law
right um so expressiveness
and efficiency and
i don't know perhaps the environment
that it came with as well which was unix
so it meant if you wrote a program it
could be used on all those computers
that ran unix and that was all of those
computers because they were all written
in c
and that was unix the operating system
itself was portable as were all the
tools
so it all worked together again in one
of these things where
things fed on each other in a positive
cycle
what did it take to write sort of a
definitive
book probably definitive a book on all
of program like
it's more definitive to a particular
language than any other book on any
other language
and did two really powerful things which
is
popularized the language at least from
my perspective maybe you can correct me
and
second is created a standard
of how you know the the how this
language is supposed to be used and
applied so what did it take did you have
those kinds of ambitions in mind when
we're working on that this is some kind
of joke
no of course not um so it's an accident
it's an accident of uh
of timing skill and just luck a lot of
it is it
clearly uh timing was good now dennis
and i wrote the book in 1977
yeah right um and at that point unix was
starting to spread
i don't know how many there were but it
would be dozens to hundreds of unix
systems
um and c was also available on other
kinds of computers that had nothing to
do with unix and
so the language had some potential
um and there were no
other books on c and bell labs was
really the only source for it and dennis
of course was authoritative
because it was his language and he had
written the uh reference manual
which is a marvelous example of how to
write a reference manual really really
very very well done so i twisted his arm
until he agreed to write a book and then
we wrote a book
and the virtue or advantage at least i
guess of going first is that then
other people have to follow you if
they're going to do anything
and i think it worked well because
dennis was a superb writer i mean he
really really did and that the reference
manual in that book is
his period i had nothing to do with that
at all
um so just crystal clear prose and
very very well expressed um and then he
and i
i wrote most of the expository material
and then he and i sort of did the usual
ping-ponging back and forth
you know refining it but i spent a lot
of time trying to find examples that
would sort of hang together and that
would tell people what they might
need to know at about the right time
that they should be thinking about
needing it
and i'm not sure it completely succeeded
but it mostly
worked out fairly well what do you think
is the power of example i mean you're
you're the creator at least one of the
first people to do the hello world
program
which is like the example if if aliens
discover our civilization hundreds of
years from now it'll probably be hello
world programs
just to have broken robot communicating
with them with the hello world
so what and that's a representative
example so what
what do you find powerful about examples
i think
a good example will tell you how to do
something
and it will be representative of you
might not want to do exactly that but
you will want to do something that's at
least in that same
general vein and so a lot of the
examples
in the c book were picked for these very
very simple straightforward text
processing
problems that were typical of unix i
want to
read input and write it out again
there's a copy command i want to read
input and do
something to it and write it out again
there's a grab
and so that kind of find things that are
representative of what people want to do
and spell those out so that they can
then take those
and see the the core parts and
modify them to their taste and i think
that a lot of programming books that i i
don't look at
programming books a tremendous amount
these days but when i do a lot of don't
do that
they don't give you examples that are
both
realistic and something you might want
to
do some of them are pure syntax here's
how you add three numbers well come on i
could figure that out
tell me how i would get those three
numbers into the computer and how we
would do something useful with them
and then how i put them back out again
neatly formatted
and especially if you follow that
example there is something magical of
doing something that
feels useful yeah right and i think it's
the attempt and it's absolutely not
perfect
uh but the attempt in all cases was to
get something that was going to be
either directly useful or would be very
representative of
useful things that a programmer might
want to do
but within that vein of fundamentally
text processing reading text
doing something writing text
you