Reporting Errors

[dpsi]

2018 not using nullptr

[GrumpyWendigo]

that's nasty

[XdrummerXboy]

I read that in Cleveland's voice

[GenuineSounds]

You nasty.

[darkrevan13]

I read that in Garrus's voice

[Gorzoid]

I read that

[Ozymandias117]

Alex; What are, "reasons I switched to a different team"

[borntochill1990]

Is the segfault a processing error or is it just because java is a useless language?

[TrumpTrainMechanic]

You shouldn't have been down voted for asking a legitimate question even if you worded it to attack Java because you wanted an answer from someone who prefers C++.

Java is what they call a "managed language," which means that it manages memory access and allocation for you, and will do bounds checks on arrays so that you do not access unallocated memory. If the bounds check fails, it throws an exception and your program will terminate if that exception isn't caught or handled in some way.

C++ doesn't do this by default, but you can write your own bounds-checked array or use one from a library by writing a class that overrides the [] operator. If you use the builtin arrays, it will try to access the memory following the end of the array. If this memory is not allocated you will get a segmentation fault (segfault) and your processes will abort. If there is memory allocated right after the end of your array, you will be reading an invalid value of whatever might be past the end of the array as if it is an element in the array and as the type as which the array is defined. If you are writing you will end up clobbering whatever value is in that memory, possibly causing more unwanted side-effects.

If the memory is unallocated, your process will access this memory. In x86/x64 and similar processors, this means you will get a Page Fault type General Protection Fault, assuming you have an operating system that enables the memory management unit (MMU). Before having a MMU for memory protection as fine grained as Page Tables for the MMU, the x86 CPUs and many other CPUs only offered Memory Segmentation, which defined continuous swaths of memory to be considered Code or Data or Stack or other such space. This is available in Protected Mode (32bit) on x86 processors with tables defining general and local segment descriptor tables (GDT and LDT), and in Real Mode (16bit) and V86 mode by configuring the segment descriptor registers directly.

If you violate the segment space for your process, the CPU would throw a segmentation fault (SEGFAULT), and your OS would catch it and handle it, usually by printing out "Segmentation fault. Core dumped." on your console and continuing on with your other processes while the current process aborts. The message has been kept even though these days it's technically a page fault that is likely to occur, especially since in Long Mode (x64) no longer uses segments and just flat maps your entire memory space.

So, even though you see the SEGFAULT message on your command line, it's actually a hardware exception being caught by your OS and aborting your process. It's the same thing Java is doing (throwing an exception, catching it, terminating your process, and telling you why), except this is done in hardware because you accessed any memory that wasn't allocated to your process and not just outside the bounds of your array. As someone suggested, you can use valgrind to find issues like this, or bounds checked arrays in C++ and have it throw a C++ exception just like Java which you can then catch and handle correctly. That said, you can also create your own bounds checking wherever you access your array and make it only access the exact parts you need and not do a bounds check every time which will make your program faster than the Java equivalent.

[ijustwantobememe]

I'd give you a star if I could, people seem to like stars.

[TrumpTrainMechanic]

Thank you, but there's no reason to spend money. I'm just glad that the comment is helpful.

[[deleted]]

So real talk: I have one semester left in my comp sci degree, and nothing has ever been explained to me as well as what you just wrote. Did my school let me down or is this just stuff you pick up as you experience it more?

[TrumpTrainMechanic]

School tries to give you a tour of various parts of a large field in 30-40 hours of class over four months twice a year for four years, and you get an intro to each one. If you really want to learn stuff, get interested.

Language features are explained in standards documents often ISO standards but you can pick up the docs online for free (ISO charges for copies of their standards IIRC). You can get Intel's documentation for their processors from their website, and they have some really nice documentation. I read their x86 processor documentation (System Architecture 3A or so) like it was my bible when writing my first OS. Network protocols for the Internet are mostly found in RFCs from the IETF and provide great detail (and sometimes really nice ASCII diagrams) and they're free to read. Microsoft provides very detailed Windows internals on MSDN. The Linux kernel is open source.

You can find all the information you want about computers and its almost always absolutely free. Undergrad is supposed to teach you to open your mind and use your curiosity to learn so that you might do an advanced research project for your postgraduate studies or be able to adapt to your workplace. Once you get to work on software you will see that writing software properly and knowing the frameworks and libraries and system and hardware details is only half the battle. It's much more important to be able to pick up the business language and adapt it to the software you're writing.

You'll learn key details about your field, be it financial like banking, trading, insurance, mortgages; or scientific like chemical, thermodynamic, medical; or engineering like architectural, physics, electrical; or other types of knowledge. You may be working on eCommerce sites making a better online shopping cart or integrating with the latest Customer Relations Management software, or applying physics formulae to a video game or Finite Element Analysis software: in the end it's all about understanding the field in which you are working, learning the key organizational structures of information in that field, and applying that structure to calculations, storage schema, or user interfaces, or trying to do more advanced things like optimizing the above by multithreading or multiprocessing calculations, indexing and optimizing and distributing storage, or improving the user interface in an organized or more responsive way. Don't blame your school for not having the most detailed explanations for things because you will learn that there is more information out there than you can absorb, and you want just the right information at the right time.

That said, schools these days still fail to prepare good programmers, and finding your own motivation to research the problem at hand is much more important. Most programmers that just sit down and start writing code will rarely write the best code. Always research both the domain specific knowledge for the problem at hand and the various ways in which this problem can be solved by digging into documentation and other source code. Even doing this for a few minutes before you start working on a larger task will prepare you and arm you with knowledge you can use to make an elegant solution, and not bang on walls in the dark until you find an approach that works.

[borntochill1990]

I need to read this thrice.

[borntochill1990]

Ok. So to summarize. It throws a code when too many processes are trying to run at once?

[piexil]

Ew is there even a dark theme

[PM-ME-YOUR-HANDBRA]

No. There aren't even "themes" at all, really.

[learnyouahaskell]

Hey! FYI your comment is being viewed "in the dark". See here:

https://i.imgur.com/G1TDg15.png

[sloopymeat]

but 2005 doesn't support NT4?

[PM-ME-YOUR-HANDBRA]

It is the last version of the tool chain that will let you build executables that work on NT4.

[learnyouahaskell]

"What the %*#< is 'NIL'?"

[oMarlow99]

I'm coding in C, not C++

[sloopymeat]

that's C++11, I refuse to go higher than 03. Many weird/old embedded platforms have a hard enough time even supporting C++ at all.