how to write bug free code

how to write bug free code

The Class Methodology 5. A New Heap Manager 6. Within these constraints, good programmers prefer to make functionality buggy and incomplete while keeping the design clean and easy to maintain. There are exceptions, of course, where the business prioritizes functionality above everything else, but such situations happen very rarely if the business is smart. This model allows for more than 64K of data and less than 64K of code. It is ideal for small programs that crunch through a lot of data.

The program is still fast, but there is a slight speed penalty for accessing far data. The medium memory model. This memory model allows for less than 64K of data and more than 64K of code. This is the memory model that Microsoft recommends using for programming in Windows. It allows for lots of code and a small amount of data. By using mixed-model programming, you can gain access to more than 64K of data. The large memory model. This allows for more than 64K of data and more than 64K of code.

It is the memory model that most closely matches flat memory model architectures. Sign Up Now. Writing bug-free code is a good trait, but it remaining as the first focus will only harm your overall program.

Good programmers make sure that the bugs they introduce are cheaper and do not contribute to the technical debt significantly. Save my name, email, and website in this browser for the next time I comment.

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These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may have an effect on your browsing experience. This is true, because there are no elements between index 0 and index -1 , and the sum of 0 numbers is 0. That is, the sum of all the elements of an empty array is 0. If the array is not empty, the body of the loop will execute, and the condition will be evaluated again.

At this point I is true we don't consider loop conditions with side effects, more on that later. The condition of the loop is also true, because otherwise, we wouldn't have entered the loop body. What we have to prove is:. That is, the invariant is preserved across iterations. What's the condition to use between the statements? We have a slight problem here, because we can't prove that array[i] is a valid expression. Additionally, we need array to be an allocated array with at least length elements let's denote this condition with T to save space.

Therefore, we have to modify our invariant to include this information. Note this important step in understanding the code we write. We didn't make all our expectations explicit. This is how bugs sneak in.

With this new invariant we have to start over. Is it true when execution hits the loop? This is true. Is it preserved across iterations? We know that array[i] is valid, because of the constraints on i included in the condition.

Well, the first thing a sharp QA mind would try is: What about null input? Or input that doesn't contain any square brackets?

It throws an exception! At this point, the developer might protest, "Well this function is only meant to read lines of a specific format.

They should never run on such bad input! In my opinion, the solution to both is better code specifications. OK, I hear your groans already. But I'm not talking about the high-level feature requirements document that you have to wait for a product manager to write up.

I'm talking about the short, quick documentation that any developer can write for every low-level unit of code i. Problem 1 can be solved directly by specifying the kinds of inputs parseRecord should accept we'll get back to this later. What about problem 2? Well, we can use the well-specified behaviour of the methods that our code calls - like String. Disclaimer: I am not an expert in formal methods for verifying software.

I will however show you one way to do it. The method is to write assertions in between each line of code. The assertions are logical statements not code that runs , and they must always be true at that point of the code's execution.

The first assertion we write will be at the entrance of the function, before any lines of code are executed. The develop their software and when they reach certain level of low priority bugs they simply release the product and solve those later. Unless you're developing something more complex than a simple calculator, It's not possible to avoid bugs all together.

Hell even NASA has redundancy on their vehicles and bugs as well. Although they have much rigorous testing to avoid catastrophic failures. But nonetheless even they have bugs in their software. Not wired nor wireless. So just as there are no perfectly secure system, there's no complex bug-less system. I only see answers about us being human and prone to err, which is very true I think you can write bug-free programs, but those typically are programs that you have written already 10 or 12 times.

The 13th time you write the same program from scratch, you already know how to do it: you know the problem, you know the techniques, you know the libraries, the language All the patterns are there, at all levels. This happens to me with very simple programs because I teach programming. They are simple for me, but hard for the students. And I am not talking about solutions to problems I have done many, many times in the blackboard.

Of course I know those. I write these programs with no planning and they just work, and I feel I know all the details, I don't need TDD at all. I get a couple or three compilation errors mostly typos and other things like that and that's it. I can do this for small programs, and I also believe that some people can do that for more complicated programs.

I think people like Linus Torvalds or Daniel J. Bernstein have such clarity of mind, they are the closest you can get to a bug-free coder. If you understand things deeply I think you can do it. I can only do this for simple programs, like I said. My belief is that if you always try to do programs that are far above your level I've spent years doing just that , you will get confused and make mistakes.

Big mistakes like those in which you suddenly realise that your solution cannot work, when you finally understand the problem, and have to make changes so complicated that they might stop you from solving your problem or make the code awful.

TDD is for this cases, I believe. You know that you don't grok the problem you are tackling and therefore put tests everywhere to make sure that you have a strong base. TDD doesn't solve the 10, feet vision, though.

You might walk in circles with perfectly clean code all the time. However, if you try to do something that is new but that is just above your level, you might get your program perfect or almost perfect. I think it is really difficult to know what programs are in your "knowledge frontier", but in theory that is the best way to learn. I rewrite programs from scratch a lot, actually. Some people do, but you need a lot of time and patience because the third time you repeat a non-trivial program you don't get excited like the first time.

So my advice is: don't think you understand something until you can write a program bug-free just for that thing. And then try to combine two of those concepts you know deeply into the same program. I'm almost sure you will get it right the first time. One of the best ways is to rewrite non-trivial software, something that took a lot of effort the first time I am doing this with Android apps right now.

Every time I start again I change something or add stuff, just to add a little fun, and I can tell you I get better and better and better Maybe think more about the nature of the bugs that you get.

If the bugs are generally minor oversights then a focus on better testing and a bit of code proof-reading would help. If the bugs tend to be due to suboptimal programming decisions, though, then maybe putting more effort into better design is required. In this case, I think it's possible to be too dependent on testing to raise the quality of the software, because applying a patch to deficient code can just make future maintenance more complicated.

On the one hand you get less bugs as you find and fix them, but on the other hand you prepare the ground for future bugs. One way to judge if you have an issue with oversights or an issue with design might be to consider how much effort is required to fix the bugs.

If the fixes tend to be large, or you feel that you don't understand them well, that points the figure at code design that can be improved.

That I think comes down to a sort of good taste about code, which you can develop with practice and review, and reading about people with similar problems. Ultimately, it is futile to expect no bugs at all, but there's no harm in trying to reduce your bug count unless you already have it at some low level, and then it becomes a trade-off between your time and the time of whoever finds bugs that you don't catch. In my opinion the best book to learn that is: GOOS.

Note: Take the article how to write bug free code with a grain of salt. Writing bug-free code is impossible. How to write bug free code best developers focus on making code that is reliable and maintainable, but anyone who says a piece of code is bug-free has not how to write bug free code their research. Research has shown that there is a factor of 20 between the productivity of the best and the worst programmers. That how to write bug free code, top programmers work 20 times faster than the worst ones, how to write bug free code around 5 to 10 times faster than average programmers. This means that a very good developer can do in a day what others may need a month for. There are a couple of ways to increase productivity, how to write bug free code the most important factor is accuracy. Accuracy strongly correlates with development speed. The best developers distinguish themselves by writing bug free code right away. If you are able to write code that does not contain any mistakes, you don't have to waste your time hunting bugs. Ever wondered why that guy at the next table who works so leisurely gets things done a lot faster than you? That's because he does the right thing at the first try. It is of course impossible to prevent bugs entirely, but:. So how to write bug free code? You'd think that most bugs are introduced by thoughtlessness, but in fact, most bugs are introduced by the programmer not entirely understanding his own code. If you get a NullPointerException in Java, that's usually not because you forgot to think about null references, but because you didn't really understand the role of the variable that was null. To write bug free code, you first have to learn how to prove that a piece of code works. A lot of adobe photoshop 8.0 free download full version for windows 7 study these techniques at the university, but they never really learn to apply them in real-life coding. Other developers especially those without a degree never learn formal methods in the first place, so it's how to write bug free code good point to start. It may look too theoretical at first sight, but this is the key to bug free programming. Let's start out with a very simple program. how to write bug free code Communicate. Not only within your team, but in general. Use proper tooling. Be eager to learn. Don't only fix. › what-are-bugs-and-how-to-write-bug-free-code To write bug free code, you first have to learn how to prove that a piece of code works. A lot of developers study these techniques at the university, but they never​. Is it possible to write code with zero bugs? In the race of writing bug free code everyone has forgotten other important aspects of programming. In I was studying Software Development for Nuclear Power Plants in the ex-​USSR and my teacher, Laritza Nicolaevna, asked me to write a bug free. › questions › how-to-be-a-z. You cannot write bug-free code if you do not thoroughly understand the architecture of the system, and the pitfalls of that architecture. E.g. if you. At this point, the developer might protest, "Well this function is only meant to read lines of a specific format. Reading the documentation, we find that the two substring methods we use can throw IndexOutOfBoundsException! In this interview, you will be given a list of bugs to find and patch as well as identifying other potentially problematic code along the way. Although this particular technique is not for everyone developers can benefit from it during complicated programming projects. Let's move on to conditionals. A lot of what we do as engineers centers around finding and patching bugs which are reported to us from various sources. The interviewer will ask you questions about yourself and how you deal with certain types of situations. If we can prove that. Static analysis tools do exactly this. We have proven that the program gives correct results if it terminates. how to write bug free code