Tony Hoare quotes:

An ultimate joint challenge for the biological and the computational sciences is the understanding of the mechanisms of the human brain, and its relationship with the human mind.

There are two ways of constructing a software design; one way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult.

I conclude there are two ways of constructing software design: one way is to make it so simple there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies."

Premature optimization is the root of all evil in programming.

It is easy to predict that some of the discoveries of research directed towards Grand Challenges - but only the most unexpected ones, and at the most unexpected times - will be the basis of revolutionary improvements in the way that we exploit the power of our future computing devices.

There are two methods in software design. One is to make the program so simple, there are obviously no errors. The other is to make it so complicated, there are no obvious errors.

We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.

A single human brain has about a hundred million nerve cells... and a computer program that throws light on the mind/brain problem will have to incorporate the deepest insights of biologists, nerve scientists, psychologists, physiologists, linguists, social scientists, and even philosophers.

Programmers are always surrounded by complexity; we cannot avoid it.... If our basic tool, the language in which we design and code our programs, is also complicated, the language itself becomes part of the problem rather than part of its solution.

Some problems are better evaded than solved.

I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.

The price of reliability is the pursuit of the utmost simplicity. It is a price which the very rich may find hard to pay.

The unavoidable price of reliability is simplicity.

I call it my billion-dollar mistake. It was the invention of the null reference in 1965.

I don't know what the language of the year 2000 will look like, but I know it will be called Fortran.

At first I hoped that such a technically unsound project would collapse but I soon realized it was doomed to success. Almost anything in software can be implemented, sold, and even used given enough determination. There is nothing a mere scientist can say that will stand against the flood of a hundred million dollars. But there is one quality that cannot be purchased in this way--and that is reliability. The price of reliability is the pursuit of the utmost simplicity. It is a price which the very rich find most hard to pay.

Here is a language so far ahead of its time, that it was not only an improvement on its predecessors, but also on nearly all its successors.

I was eventually persuaded of the need to design programming notations so as to maximize the number of errors which cannot be made, or if made, can be reliably detected at compile time.

In the development of the understanding of complex phenomena, the most powerful tool available to the human intellect is abstraction. Abstraction arises from the recognition of similarities between certain objects, situations, or processes in the real world and the decision to concentrate on these similarities and to ignore, for the time being, their differences.

Inside every large program is a small program struggling to get out.

The job of formal methods is to elucidate the assumptions upon which formal correctness depends.

The real value of tests is not that they detect bugs in the code but that they detect inadequacies in the methods, concentration, and skills of those who design and produce the code.

What is the central core of the subject [computer science]? What is it that distinguishes it from the separate subjects with which it is related? What is the linking thread which gathers these disparate branches into a single discipline. My answer to these questions is simple -it is the art of programming a computer. It is the art of designing efficient and elegant methods of getting a computer to solve problems, theoretical or practical, small or large, simple or complex. It is the art of translating this design into an effective and accurate computer program.

You cannot teach beginners top-down programming, because they don't know which end is up.