with C.a.R. hoare
C.A.R. Hoare, developer of the Quicksort algorithm and a lifelong contributor to the theory and
design of programming languages, discusses the practical application of his theoretical ideas.
The CoMpUteR hiStoRY
Museum has an active program
to gather videotaped histories from people who have
done pioneering work in
this first century of the information
age. These tapes are a rich aggregation
of stories that are preserved in the collection, transcribed, and made available on the Web to researchers, students, and anyone curious about how
invention happens. The oral histories
are conversations about people’s lives.
We want to know about their upbringing, their families, their education,
and their jobs. But above all, we want
to know how they came to the passion
and creativity that leads to innovation.
Presented here are excerptsa from
an interview with Sir Charles Antony
Richard Hoare, a senior researcher at
Microsoft Research in Cambridge, U. K.
and Emeritus Professor of Computing
at Oxford University, conducted in September 2006 by Jonathan P. Bowen, the
chairman of Museophile Limited, and
Emeritus Professor at London South
What did you want to
be growing up?
I thought I would like to be a writer. I
didn’t know quite what I was going to
be writing, but at school I was a rather
studious and uncommunicative child,
and so everybody called me “Professor.”
I found the works of Bernard Shaw very
inspiring. He’s of course an iconoclast,
so he would appeal to an adolescent.
Also Bertrand Russell, who wrote on
social matters as well as philosophical
and mathematical matters.
a Oral histories are not scripted, and a transcript
of casual speech is very different from what
one would write. I have taken the liberty of
editing and reordering freely for presentation.
For the original transcript, see http://archive.
What was your first
exposure to computers?
I began thinking about computers as
a sort of philosophical possibility during my undergraduate course at Oxford University. I took an interest in
mathematical logic, which is the basis
of the formal treatment of computer
programming. I was sufficiently interested that one of my few job interviews
was with the British Steel just after I
finished my university course in 1956.
I was attracted by their use of computers to control a steel milling line. A
little later I attended an interview at
Leo Computers Ltd. in London, who
were building their own computers
to look after the clerical operations of
their restaurant chain. But I didn’t follow up on either of those prospects of
What was the first
program you wrote?
In 1958 I attended a course in Mercury
Autocode, which was the programming
language used on a computer that Oxford University was just purchasing
from Ferranti. I wrote a program that
solved a two-person game using a technique which I found in a book on game
theory by von Neumann and Morgen-stern. I don’t know whether it worked
or not. It certainly ran to the end, but I
forgot to put in any check on whether
the answers it produced were correct,
and the calculations were too difficult
for me to do by hand afterward.
Photogra Ph courtesy of microsoft research
What was programming
like in those days?
Very different from today. The programs were all prepared on punched
cards or paper tape. It might take a day
to get them punched up from the cod-