Best 93 quotes of Edsger Dijkstra on MyQuotes

About the use of language: it is impossible to sharpen a pencil with a blunt axe. It is equally vain to try to do it with ten blunt axes instead.

A convincing demonstration of correctness being impossible as long as the mechanism is regarded as a black box, our only hope lies in not regarding the mechanism as a black box.

Aim for brevity while avoiding jargon.

A most important, but also most elusive, aspect of any tool is its influence on the habits of those who train themselves in its use. If the tool is a programming language this influence is, whether we like it or not, an influence on our thinking habits.... A programming language is a tool that has profound influence on our thinking habits.

APL is a mistake, carried through to perfection.

APL is a mistake, carried through to perfection. It is the language of the future for the programming techniques of the past: it creates a new generation of coding bums.

A programming language is a tool that has profound influence on our thinking habits.

Are you quite sure that all those bells and whistles, all those wonderful facilities of your so called powerful programming languages, belong to the solution set rather than the problem set?

... as a slow-witted human being I have a very small head and I had better learn to live with it and to respect my limitations and give them full credit, rather than to try to ignore them, for the latter vain effort will be punished by failure.

Besides a mathematical inclination, an exceptionally good mastery of one's native tongue is the most vital asset of a competent programmer.

Beware of "the real world". A speaker's apeal to it is always an invitation not to challenge his tacit assumptions.

Computer science has as much to do with computers as astronomy has to do with telescopes.

Computer science is no more about computers than astronomy is about telescopes, biology is about microscopes or chemistry is about beakers and test tubes. Science is not about tools. It is about how we use them, and what we find out when we do.

Don't blame me for the fact that competent programming, as I view it as an intellectual possibility, will be too difficult for the average programmer, you must not fall into the trap of rejecting a surgical technique because it is beyond the capabilities of the barber in his shop around the corner.

Don't compete with me: firstly, I have more experience, and secondly, I have chosen the weapons.

Elegance is not a dispensable luxury but a factor that decides between success and failure.

FORTRAN, the infantile disorder, by now nearly 20 years old, is hopelessly inadequate for whatever computer application you have in mind today: it is now too clumsy, too risky, and too expensive to use.

How do we convince people that in programming simplicity and clarity - in short: what mathematicians call elegance - are not a dispensable luxury, but a crucial matter that decides between success and failure?

I don't need to waste my time with a computer just because I am a computer scientist.

If debugging is the process of removing software bugs, then programming must be the process of putting them in.

If in physics there's something you don't understand, you can always hide behind the uncharted depths of nature. You can always blame God. You didn't make it so complex yourself. But if your program doesn't work, there is no one to hide behind. You cannot hide behind an obstinate nature. If it doesn't work, you've messed up.

If there is one 'scientific' discovery I am proud of, it is the discovery of the habit of writing without publication in mind.

If we wish to count lines of code, we should not regard them as "lines produced" but as "lines spent.

I mentioned the non-competitive spirit explicitly, because these days, excellence is a fashionable concept. But excellence is a competitive notion, and that is not what we are heading for: we are heading for perfection.

Industry suffers from the managerial dogma that for the sake of stability and continuity, the company should be independent of the competence of individual employees.

I now have had my foggy crystal ball for quite a long time. Its predictions are invariably gloomy and usually correct, but I am quite used to that and they won't keep me from giving you a few suggestions, even if it is merely an exercise in futility whose only effect is to make you feel guilty.

In passing I draw attention to another English expression which often occurs in Dutch texts: "the real world". In Dutch - and I am afraid not in Dutch alone - its usage is almost always a symptom of a violent anti-intellectualism.

In the good old days physicists repeated each other's experiments, just to be sure. Today they stick to FORTRAN, so that they can share each other's programs, bugs included.

In their capacity as a tool, computers will be but a ripple on the surface of our culture. In their capacity as intellectual challenge, they are without precedent in the cultural history of mankind.

In the software business there are many enterprises for which it is not clear that science can help them; that science should try is not clear either.

In the wake of the Cultural Revolution and now of the recession I observe a mounting pressure to co-operate and to promote "teamwork." For its anti-individualistic streak, such a drive is of course highly suspect; some people may not be so sensitive to it, but having seen the Hitlerjugend in action suffices for the rest of your life to be very wary of "team spirit." Very.

In this respect a program is like a poem: you cannot write a poem without writing it. Yet people talk about programming as if it were a production process and measure "programmer productivity" in terms of "number of lines of code produced". In so doing they book that number on the wrong side of the ledger: we should always refer to "the number of lines of code spent".

I think of the company advertising "Thought Processors" or the college pretending that learning BASIC suffices or at least helps, whereas the teaching of BASIC should be rated as a criminal offence: it mutilates the mind beyond recovery.

It is a mistake to think that programmers wares are programs. Programmers have to produce trustworthy solutions and present it in the form of cogent arguments. Programs source code is just the accompanying material to which these arguments are to be applied to.

It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration.

I would therefore like to posit that computing's central challenge, how not to make a mess of it, has not yet been met.

John von Neumann draws attention to what seemed to him a contrast. He remarked that for simple mechanisms, it is often easier to describe how they work than what they do, while for more complicated mechanisms, it is usually the other way around.

LISP has jokingly been described as "the most intelligent way to misuse a computer." I think that description is a great compliment because it transmits the full flavour of liberation: it has assisted a number of our most gifted fellow humans in thinking previously impossible thoughts.

Many mathematicians derive part of their self-esteem by feeling themselves the proud heirs of a long tradition of rational thinking; I am afraid they idealize their cultural ancestors.

Mathematicians are like managers - they want improvement without change.

Object-oriented programming is an exceptionally bad idea which could only have originated in California.

Our intellectual powers are rather geared to master static relations and that our powers to visualize processes evolving in time are relatively poorly developed. For that reason we should do (as wise programmers aware of our limitations) our utmost to shorten the conceptual gap between the static program and the dynamic process, to make the correspondence between the program (spread out in text space) and the process (spread out in time) as trivial as possible.

PL/1, the fatal disease, belongs more to the problem set than to the solution set.

Please don't fall into the trap of believing that I am terribly dogmatical about the go to statement. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline!

Probably I am very naive, but I also think I prefer to remain so, at least for the time being and perhaps for the rest of my life.

Production speed is severely slowed down if one works with half-time people who have other obligations as well. This is at least a factor of four; probably it is worse.

Programming in Basic causes brain damage.

Programming is one of the most difficult branches of applied mathematics; the poorer mathematicians had better remain pure mathematicians.

Program testing can be used to show the presence of bugs, but never to show their absence!

Progress is possible only if we train ourselves to think about programs without thinking of them as pieces of executable code.