Bjarne Stroustrup on C++

Editor's Note

This is an HTML version of a note by Bjarne Stroustrup addressing various perceptions about and opinions on C++. My editing consisted of: My goal was to maintain the essence of the article, while making it readable by standard WWW browsers.

Mike Lutz


This message is a response to a lot of outrageous inaccuracies, innuendo, rudeness, and flat-out false statements about C++ and its user community. The most dignified response would be a solid technical paper documenting the beauty and power of C++. However, people who believe even part of the rubbish posted about C++ will be unlikely to invest the time to get hold of such a paper and read it. In fact, the stated purpose of some of the worst postings has been to warn people against gaining an under- standing of C++. Also, there is no shortage of material describing C++ and its uses. Consequently, I chose to respond directly.

I consider a large portion of the bashing of C++ and the C++ users unwarranted, ill-informed, self-serving, and intellectually dishonest. Sadly, one must expected some mud to be thrown at anything successful, but I think some posters have gone too far in their attacks on C++.

Please note, that I am NOT claiming C++ is perfect, that I am NOT saying that every critic of C++ is dishonest or ill-informed, that I'm not suggesting people should stop discussing C++'s strengths and weaknesses (where relevant), and that I am NOT telling you to stop using your favorite programming language and use C++ instead.

I am asking people to clean up their act, to be honest and up-front with their aims and motives, to refrain from unsupported derogatory statements, to avoid ``have you stopped beating your wife'' style of demagogy, and to get a minimum of acquaintance with C++ before starting to give advice (positive or negative) about it.

If you - like most people - have not been engaging in disreputable debating practices, please don't take offense from my words; they are not aimed at you.

And do, please do, learn not only C++, but also other languages, systems, and techniques that might be helpful to your work and intellectual growth. A closed mind is a recipe for bigotry.

Personally, I have found many stimulating ideas in Ada, Algol68, CLOS, Eiffel, ML, Modula-*, Smalltalk, Simula, etc. and in code written in those languages. For most of the kind of work I do, I prefer C++, but I have never found learning a new language unrewarding. The thing to remember, though, is that a programming language - any programming language - is a means to an end (the building of systems), rather than an end in itself. Considering how to build better systems and how various languages can serve that end is a much better use of time than fighting language wars.

Please remember that a system can be ``better'' according to many different criteria. The particular purpose of a system together with the particular context of its development often have decisive effects on the judgement of a system by its builders and - more importantly - of its users.

Below, I present abbreviated versions of common unfair attacks on C++ in quotes and then comment on them. Naturally, I try to make my comments helpful to people suffering from the root causes of those of the attacks that have a basis in reality rather than being just manifestations of commercial or intellectual rivalry.

``C++ sucks''

If you think so, go use what you consider better. It may indeed be better than C++ for your purposes.

C++ is a very useful language that is used successfully by MANY people in MANY application areas. I guess that is a large part of what bothers some. By being successful, C++ offends many who have strong notions of what else ought to be successful.

The major cause of complaints is C++ undoubted success. As someone remarked:

There are only two kinds of programming languages: those people always bitch about and those nobody uses.
C++ isn't perfect. That is well known and acknowledged from the start. It is, however, a reasonably carefully thought-out language where the design is based part on acknowledged principles and part on solid experience and feedback from actual use. See my book ``The Design and Evolution of C++'' for an exposition of the aims of C++, the design process that led to the current language, the reasons for particular design decisions, etc.

I wish I had an electronic equivalent to a little duck-horn, so that a rude BEEP was triggered by every unsupported derogative statement about C++. The noise would be deafening, though. An increasing number of people seem to relish displaying their ignorance and poor manners by snide remarks and gratuitous inaccuracies.

At a recent conference, a speaker asked for a show of hands and found that twice as many people claimed to hate C++ as had ever written even a single small C++ program. The only word for such behavior is bigotry. In dealing with the current wave of C++ bashing, we should remember that bigotry is bred by ignorance and fear.

It should also be remembered that if bigotry is not opposed but allowed to fester and sow distrust real harm results.

``C++ is too complex''

C++ is much more complicated than, say, C and Pascal. However, MANY have succeeded in learning and applying C++. It has been demonstrated again and again that you don't need to be a genius to learn C++ in a reasonable time or to use C++ well. Further, it has been demonstrated that there are several distinct ways of reaching that level of competence.

So, what about C++ is hard to learn, and why? Someone knowing C well can learn Pascal in a week - and vice versa. Becoming expert - that is, learning to avoid the more common pitfalls and using common idioms of the new language - is harder. It could even take a couple of months. The reason for the easy transition is that the languages are fundamentally similar. All that needs to be learned is a bit of syntax and a few simple ways of using the new syntax. Often, this can be learned from looking at the briefest description of the language and some code. The time and effort needed is a small fraction of was originally invested in becoming an effective programmer.

This is where C++ is different. The key concepts of data abstraction and object-oriented programming are new to most people. Yes, these days most people have heard about OOP, but most have no practical experience with it and can no more do a object-oriented design than swim or bicycle based only on having read an article on the subject.

You can use C++ effectively as a more strongly type checked C with a bit of simple data abstraction and library use thrown in after a week. However, becoming comfortable with OOP/OOD takes most people much longer. Estimates of six to eighteen month for becoming really proficient are often quoted, are in line with my personal experience with new C++ projects, and are in line with experience with other languages supporting OO.

That demonstrates that the problems with notation and other language- technical details are minor. They are typically overcome within weeks. The real problems - as with any language - are conceptual: How to make a good design; not (just) how to express it.

The much touted problems with readability are again vastly overstated.

You can write obscure code in any language, and significant programs in a language you have only superficial knowledge about are always unreadable - especially if prejudice prevent you from actually trying to overcome notational barriers. A major part of readability is simply familiarity and experience.

The idea that a manager or a complete novice in a language can come even close to comprehending a significant program because some inherent virtue of a particular language is nothing more than marketing hype and self-delusion. When people make such claims I wonder what else they might believe or be willing to claim.

So why do reasonably clever and experienced people sometimes fail to learn C++ or fail to use it effectively after they have supposedly learned it? Usually because they have the wrong expectations. This actually has to be the case because I haven't found any strong correlation between what we could call smarts and becoming good C++ programmers. Some really clever programmers fail, and some supposedly mediocre ones succeed spectacularly.

The ones that fail are usually the ones who believe they know everything already. Coming to C++ with a ``C is THE language'' or ``OO means Smalltalk'' attitude is a recipe for failure. You can write in an (almost) pure C or (almost) pure Smalltalk style in C++, but that usually is not a good use of C++. Doing that involves a constant battle with the fundamental concepts of C++ and with the C++ type system. Against the fundamental structure of a language - any language - you can win Pyrrhic victories only.

Another mistake is made by people who firmly believe that THEY don't need tutorial material. ``Real programmers read only code and reference manuals.'' That attitude is a recipe for disaster with C++. Undoubtedly, someone can learn OOP from reading code - after all Alan Kay (partly) learned OO by deciphering an 80 page Simula program thinking it was Algol. However, most people are not in the same league as Alan.

Experience shows that trying to learn OOP or C++ from the ARM (``The Annotated C++ Reference Manual'') is usually a BIG mistake. It is a nice book, I can recommend t (:-), but not as a tutorial. After all, most people wouldn't try learning a natural language exclusively from a grammar plus a dictionary. Few would succeed.

Naturally, I recommend my ``The C++ Programming Language (2nd edition)'' for learning C++, but there are many other good books out there, and my book is not the best tutorial for everyone. Take advice from others who have succeeded in becoming good C++ programmers (rather than from self-proclaimed C++ haters or people without ractical C++ experience). It is a curious phenomenon to find self-proclaimed C++ haters trying to cash in on C++'s popularity by teaching C++, writing articles on C++, and even by writing C++ textbooks as their first C++ project.

Whatever you do, focus on concepts and design issues rather than language-technical details. The details will come in time provided the basic concepts are there. Try to avoid relying exclusively on ``how-to manuals'' and ``handy-hints books.'' I have even noticed people on the net who clearly were trying to learn C++ without any textbook or reference manual; such an effort must be most frustrating and have a low probability of succeeding. It is also a sad waste of time even if it - against all odds - should succeed.

Another thing to keep in mind is that C++ is not Windows, Unix, X, MacApp, Etc. These systems have their own logic and complexities distinct from those of C++. Simultaneously trying to learn event-driven user interfaces, distributed computing, OOD, and C++ is definitely hard. However, C++ is often the least complicated entity in such a collection of concepts/tools/systems/libraries. Blaming C++ for the complexity of a system used through it is not quite fair - even if C++ and its various program development environments are the most visible and tangible part of such a system.

The bottom line is that the world is VERY complex, and to some extent the tools we use reflects that. Among the tools we use, C++ is nowhere near the most complex.

Whatever the reason, and contrary to the popular doomsday scenarios, most programmers who genuinely try succeed in becoming productive C++ programmers in a reasonable time.

``C++ programmers are idiots''

When C++ was new, one of the things that pleased me most was that discussions about C++ were so much better informed than discussions about most other languages, that the understanding of key concepts were so much better in C++ groups than in, say, C and Pascal groups, and that groups such as comp.lang.c++ were so much more polite and supportive than that of other groups.

Clearly, I thought naively, C++ attracts a much better class of programmers, learning C++ helps people to absorb the key concepts of good programming/design, and the resulting success makes people more tolerant and helpful.

I was wrong. The phenomenon was real, but it had little to do with C++. In a small dedicated community, life is relatively easy. people do their homework, people have access to reasonable sources of information, gross errors and misconceptions are corrected before they can cause significant harm, compilers and teaching materials are up-to-date, etc.

This is not and cannot be the case in a multi-hundred-thousand member community: Some will be taught out of outdated or unsuitable books, some will use antiquated compilers and tools, some will be taught by charlatans, some will be remote from current and reliable news-sources, some will have unsuitable rules and regulations imposed on their work, etc. Also, in a rapidly growing community, most users will be novices.

Does this make C++ programmers idiots? or ``on average idiots?'' Not at all, but the average C++ programmer is not part of a relatively closely knit elite with access to the latest information and tools. Neither is the average C++ programmer someone with a lot of spare time for study and stimulating intellectual debate. When the number of any group goes up, the average - in every way - MUST converge towards the industry average.

Proponents of languages that still have relatively minute - and therefore relatively close-knit and well-informed user communities - are making the mistake I made: seeing the evident success and enthusiasm of their fellow ``cult members'' as a direct consequence of qualities of their favorite language. They are wrong; if - against all odds - their language should escape into the mainstream the vastly enlarged user community will get its share of the problems and failures.

Many of C++'s problems are best ascribed to problems with the scale of the user community and the scale of the problems attacked - as opposed to problems with the C++ language design.

Many of the most experienced individuals and organizations in the industry (and academia) use C++. Ascribing their choice of C++ over alternatives to stupidity, ignorance, or inexperience is arrogant and insulting - and in many cases simply wishful thinking based on a limited field of knowledge.

I still think the average C++ programmer is pretty smart, but rarely a fanatic, and usually too busy getting the work done to bother with language laws or the latest academic advances in OO type theory. Fortunately, one doesn't need to be a genius to write good C++.

``C++ is just C, but worse''

C++ can be used just like C, but it doesn't have to be and in general it isn't. Many (most?) people start with C++ as a more strongly type checked versions of C, use libraries, add a bit of data abstraction, and then progress to a more complete and effective use of the C++ specific features. That is in my experience a good way to progress, especially if you are not in an environment where genuine experience with OO in C++ is available and supported by management.

One effect of this gradual approach is that as long as the number of C++ programmers and C++ projects is growing rapidly, much (most?) C++ code will be written by people at the beginning of their personal or organizational learning curve. Their code will reflect it. However, this situation does not last - however much as detractors would like it to. All the personal and indirect experience I have indicates that people are moving right along as expected.

Talking about C/C++ as if it were one thing and ascribing every weakness of C and negative past experience with C to C++ is just plain wrong. personally, I take most uses of the compound ``C/C++'' as an indication of ignorance.

Considering C a smaller, faster, and better specified alternative to C++ is another popular fallacy. The C-like subset of C++ is as fast, as well specified, and easier to deal with than C itself. One source of popularity of this fallacy is an unwillingness by some C/Pascal-level programmers not to learn something really new. Another is wishful thinking by some proponents of more advanced languages: after all, if C++ is simply a more complicated C it cannot be a serious competitor to a more advanced language.

``C++ is useless/unreliable/dangerous because it lacks feature/property X''

Also heard as ``you can't write real/reliable/maintainable/elegant/ re-usable/object-oriented/modern software without feature X - and C++ doesn't have X.''


Once you - as many - have seen a few dozen large industrial C++ projects completed on time, as budgeted and going through maintenance as hoped for, clever arguments based on the necessity of individual language features - invariably features absent in C++ - lose their credibility. Such arguments remain interesting sources for ideas for improvements of C++, but their central sales/propaganda message is fundamentally discredited.

Over the years C++ has been deemed useless because it lacked (among other things) type checking, metaclasses, multiple inheritance, garbage collection, generics, concurrency support, exceptions, co- and contra-variance, dynamic linking, typecase switches. Simultaneously, if was - often by the same people - deemed useless because it was too complicated and had too many features. At the same time, a steady and increasing stream of projects were successfully completed in C++.

My firm conclusion is that no single feature is truly necessary. Much more successful software has been written in languages proclaimed BAD, than has been written in languages acclaimed as saviors of suffering programmers; much more.

Also, each time C++ has acquired another feature - according to my original view of how the language should evolve - the absolutely essential feature people used as proof of C++'s fatal weakness changed.

The real driving logic seems to be:

If feature X is in <<favorite language>> and not in C++, it MUST be fundamental to <<favorite buzzword>>.
That is backwards and illogical, but it makes commercial and psychological sense. After all, if <<favorite language>> didn't have such a killer feature arguing against C++ in a simple-minded manner could be unpleasantly hard. One of the oldest and most disreputable tricks in the book is to define OO so that <<favorite language>> and no other language really supports OO. Since every neat feature can be illustrated by a neat example that can't be done without some ugliness in a language that doesn't have the feature, the redefine-OO trick always takes in a few suckers.

Fortunately, these ``neat features'' rarely prove as essential in practice as their proponents claim they are in theory.

If no feature is essential, then why use any features? You can in theory write anything in machine code, and apparently get anything to work in the real world using C. However, why should you where there is a better alternative available? Many people strongly prefer C++ over procedural languages such as C and Pascal and deem the feature set provided by C++ close to essential for their applications. A feature need not be essential to be helpful. The set of features provided by C++ is such that aspects of most major features get used in most major programs - directly or indirectly.

I do not consider the set of features in C++ excessive; where a genuinely needed feature is missing from a programming language, the result isn't that the programmer has to understand less to work on a system; the result is that the complexities gets represented in the code itself rather than in a common form in a programming language. A major benefit of supporting a feature directly in a language or in a standard library is that much of the effort needed to understand one system will pay off when looking at another system where similar language and library features have been used. Such benefits are far harder to achieve when mechanisms are provided through code in a simpler language.

Remember that many C++ features are there primarily to allow library building. Not every feature needs to be used directly by every user, nor does every feature have to be examined in detail by every tutorial.

``C++ is not Object-oriented''

C++ supports object-oriented programming (as defined by most people). C++ supports it pretty well for real-world applications. Its type system and general model of the world are coherent and relevant to real applications.

The proof of the pudding is in the eating, so I consider the fact that many large projects have been completed using C++ much more significant than the fact that C++ doesn't conform to the latest fashion of OO theology.

Have a look at the ``Design Patterns'' book by Gamma for examples of elegant designs clearly expressed in relatively straightforward C++.

I observe that there are a lot of myths about what features C++ has and doesn't have, and also about the essential soundness of the features that people (mostly) agree that it does have. Many posters and even many writers of academic papers really ought to update their knowledge of C++. It would be unfair to seriously complain just because someone didn't know about a feature added to the upcoming C++ standard sometime during the last year or a feature for which an implementation wasn`t generally available. However, I see claims based on the 1985 edition of ``The C++ Programming Language.'' That - especially when comparisons are made with experimental languages - is totally misleading. Doing so in 1994 is intellectual sloppiness bordering on dishonesty.

If comparing C++ to a widely distributed language, at least try to compare to C++ as distributed over the last few of years (say, as described in the 1991 2nd edition of ``The C++ Programming Language.'' If comparing with an experimental language. Try to get up-to-date information - say ``The Design and Evolution of C++'' or the C++ standards committees working paper. ``The C++ Report'' and other magazines tries to keep their readers informed and tend to be only a meeting or two behind the committee. Simply relying on hostile hearsay from the net is not respectable.

``C++ compilers/tools are too buggy''

Most importantly, C++ and its various implementations have a solid core where different compilers tend to agree and where the code generated is reliably good. There are several ways of looking at a language. If your job is to write a test suite or your aim is to ``push the envelope'' of what can be done, you hit a lot of annoying bugs and variation between implementations. If your job is to build systems, you try hard to avoid the grey areas - and often succeed.

By and large, C++ compilers have been ``ok but not great'' according to the standards of their community. Some have been better. Now that the rate of language changes has decreased, I expect to see significant improvements in quality; in fact, I think I'm already seeing signs of that.

C++ tools are improving in general: For example, I had expected it to be years before I saw a C++ debugger that allowed you to stop a program at a breakpoint, rewrite a function, and then restart the program using the new function. Sun now sells a C++ system handles does that. Another example of the improved state of affairs is the wide availability of memory-leak detectors, simple browsers, and other useful program development tools.

``The C++ standards committee is out of control''
(whatever that means)

First of all, you can't believe everything you hear on comp.lang.c++, comp.std.c++, etc. In general, such forums are noisy and dominated by a relatively low number of people with strong opinions and relatively few restraints on expressing those opinions. If you consider the net in any way representative, you can get a spectacularly warped view of the world.


If you can, come to a meeting and see for yourself. There is no fee for attending a single meeting and you don't have to represent anyone to visit. Reasonably enough, you can't vote at your first meeting, though. Some members may show impatience if you try to take precious committee time without having done your homework, but you can listen and there are lots of time to discuss things outside formal sessions of the committee as a whole.

Currently, work is focused on clarification and on libraries. Just one language extension has been approved during last 8 months (adoption of the keyword ``explicit'' to suppress use of a constructor for implicit conversion) - and that's a restriction.

Much work has been done on details of name lookup, overload resolution, the type system, the memory and object models, etc. The major event in the library area was the adoption of the STL library in response to demands for containers, etc.

It might be worth mentioning that two things are happening at once: Compilers are being developed and distributed at the same time the language development is continuing. Whichever order those two things happen in, *someone* will complain. Moreover, if language development stopped, people would complain too. Already, some people are complaining because the rate of language change has slowed to a crawl.

I find it blatantly unfair when posters use strong words against ``the committee'' because it is a nebulous concept like ``the bureaucrats.'' The committee consists of hardworking individuals most of whom just happen to be unable to respond to comments in various forums. Suggestion: Don't post anything about the committee that you would be ashamed saying to me face-to-face in public.

Also, please remember that the committee members are all volunteers.

``I have heard of lots of C++ disasters''

- and senator McCarthy had heard of 200 communists in the US state department; he even claimed to have a list in his pocket.

There were a month-long thread in comp.lang.c++ and elsewhere headed ``C++ disasters.'' In fact, no genuine C++ disasters were documented. There were lots of statements on the form ``X failed and they might have used C++'' and ``X was in trouble and they used C++'' but I didn't see any message making a causal link between C++ use and failure plausible. C++ was being blamed for everything from the collapse of the US phone system (it didn't collapse and the breakdown people keep referring to occurred in a system not written in C++) to the Denver airport baggage handling system (there were/are a bit of C++ in that system but not anywhere near as much C++ as C and assembler). By the quality of the ``logic'' applied it is a marvel that C++ wasn't also blamed for the (possible) crumbling of the runway surface.

Genuine C++ failures must occur. After all, when a lot of people try some non-trivial new tool - any new gadget - some will ``fail.' I think it would be fair to guess that 10% to 20% will miss the point, find the tool not to their taste, fail to use it correctly, apply the tool in an area that it is unsuited for, etc. By that logic and the sheer weight of numbers we must conclude that more programmers have had some failure learning or using C++ than have tried any other OO language. This would explain the emotional heat of some criticisms of C++.

Many more have succeeded with C++, though, and most failures must have occurred on a small scale or we would have heard much about them - people tend not to be shy about publishing other people's failures (even in an ideal world that would be bad taste). I see no evidence that projects using C++ have a greater failure rate than projects in general. In my limited experience, the opposite seems to be the case, despite that C++ appears to be used on a disproportionate number of ``ambitious'' projects. I take this as a testimony to people's good sense, to C++'s flexibility, and to the fact that strong core of genuine C++ experts have always recommended caution in the adoption of C++ and new techniques.

On the other hand, the C++ community is somewhat to blame for not doing more to publicize their successes. As usual, the C++ community is anarchic and possesses no central focus - such as a single users group or a central coordinating organization. Usually, that is an advantage because it helps foster initiative, but when it comes to collecting and dispensing information the C++ community is at a disadvantage compared to communities focused of a single central company or organization. It would be a major benefit if someone would collect - and make easily available - brief descriptions of a couple of hundred C++ projects of significant size.

``I just don't like C++''

Fine. There are lots of things I don't like. Sometimes, I object to aesthetic aspects; sometimes something just doesn't serve my needs. If asked, I may even express my negative opinion, but rarely rudely, and never as an unprovoked attack or a snide remark about other people's work. If I am perceived to do so by lack of consideration or I slip up (nobody is perfect), I apologize.

I don't apologize for C++, though. I find C++ the best choice for a wide range of applications. If you can find the time, I encourage you to try to find out why that is. Many have found the effort worthwhile.

I wish more people would distinguish between an expression of personal opinion/taste (such as ``I just don't like C++'') and what is claimed to to be an expression of objective fact (such as ``C++ sucks''). It seems to me that a significant number of posters have difficulties distinguishing their personal opinions from objective facts.

Live and let live is a good policy. Spending a lot of emotional energy attacking other people's work is unhealthy.

Final comment:

In this note, I didn't try to present technical arguments for (or against :-) C++. You can find many of my technical arguments and opinions in my books and papers. Other good sources of information about C++ and its use are the proceedings of the USENIX C++ conferences, ``The C++ Report,'' Andy Koenig's column in JOOP, and (to a lesser extent) the OOPSLA proceedings.

I encourage the C++ community to make a greater effort to document work done in C++ and make such information more generally available (that is, not just preaching to the choir).

In general, I encourage people to popularize their favorite programming system through solid examples, rather than by merely scoring points off imagined opponents by clever programming tricks or demagogy.

In general, try to be a bit more tolerant and refrain from hyperbole. We need an intellectual honest discussion and a greater degree of professionalism in the discussion of programming and programming languages.

- Bjarne Stroustrup

Mike Lutz <>
Last modified: Mon Aug 7 16:36:15 1995