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On September 14 2016 07:40 travis wrote:
there will be multiple search terms, and I don't know what they are, so I can't set it to another string
I know I can set it to null, I was just wondering if there was a better option - is empty string a thing?
If you want to solve your problem you should not try to find some kind of hack which incidentally does what you need, instead, simply solve your problem.
You have a data structure which contains a number of data elements. You want to be able to set data elements to be temporarily invalid. Change your data structure or your data elements to allow this.
For example, instead of storing Strings directly in your list, store instances of a class which themselves have a reference to a string and a boolean field which tells you whether this data element is invalid or not. Do not try to hack things together, it will make it harder for you in the future.
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On September 15 2016 02:41 RoomOfMush wrote:Show nested quote +On September 14 2016 07:40 travis wrote:
there will be multiple search terms, and I don't know what they are, so I can't set it to another string
I know I can set it to null, I was just wondering if there was a better option - is empty string a thing? If you want to solve your problem you should not try to find some kind of hack which incidentally does what you need, instead, simply solve your problem. You have a data structure which contains a number of data elements. You want to be able to set data elements to be temporarily invalid. Change your data structure or your data elements to allow this. For example, instead of storing Strings directly in your list, store instances of a class which themselves have a reference to a string and a boolean field which tells you whether this data element is invalid or not. Do not try to hack things together, it will make it harder for you in the future.
While I mostly agree, it isn't necessarily bad to have certain values represent a certain state or a generic value. For example, -1 representing wildcards or just "All", or having a date value of 2999-01-01 being "No expiry" or something.
Important thing is to have a standard, so there isn't ambiguity for anyone else dealing with the system. And of course not to use values that would actually overlap with entries using them at face value. Which also means that your chosen values should be obvious to any observer that it's an intentionally out-of-norm entry.
Comes with it's own pitfalls, of course, but sometimes there are reasons not to overload things with flags and additional data overhead. Which all loops around to the general idea of: plan your shit.
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On September 15 2016 03:49 WolfintheSheep wrote:Show nested quote +On September 15 2016 02:41 RoomOfMush wrote:On September 14 2016 07:40 travis wrote:
there will be multiple search terms, and I don't know what they are, so I can't set it to another string
I know I can set it to null, I was just wondering if there was a better option - is empty string a thing? If you want to solve your problem you should not try to find some kind of hack which incidentally does what you need, instead, simply solve your problem. You have a data structure which contains a number of data elements. You want to be able to set data elements to be temporarily invalid. Change your data structure or your data elements to allow this. For example, instead of storing Strings directly in your list, store instances of a class which themselves have a reference to a string and a boolean field which tells you whether this data element is invalid or not. Do not try to hack things together, it will make it harder for you in the future. While I mostly agree, it isn't necessarily bad to have certain values represent a certain state or a generic value. For example, -1 representing wildcards or just "All", or having a date value of 2999-01-01 being "No expiry" or something. Important thing is to have a standard, so there isn't ambiguity for anyone else dealing with the system. And of course not to use values that would actually overlap with entries using them at face value. Which also means that your chosen values should be obvious to any observer that it's an intentionally out-of-norm entry. Comes with it's own pitfalls, of course, but sometimes there are reasons not to overload things with flags and additional data overhead. Which all loops around to the general idea of: plan your shit.
It is generally a bad idea to use a single variable to express multiple things. Exceptions can be made if you're working in a low memory environment and such, but usually it is better to keep stuff separate until you run into a compelling reason not to. Otherwise: what can go wrong will go wrong.
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On September 15 2016 03:55 spinesheath wrote:Show nested quote +On September 15 2016 03:49 WolfintheSheep wrote:On September 15 2016 02:41 RoomOfMush wrote:On September 14 2016 07:40 travis wrote:
there will be multiple search terms, and I don't know what they are, so I can't set it to another string
I know I can set it to null, I was just wondering if there was a better option - is empty string a thing? If you want to solve your problem you should not try to find some kind of hack which incidentally does what you need, instead, simply solve your problem. You have a data structure which contains a number of data elements. You want to be able to set data elements to be temporarily invalid. Change your data structure or your data elements to allow this. For example, instead of storing Strings directly in your list, store instances of a class which themselves have a reference to a string and a boolean field which tells you whether this data element is invalid or not. Do not try to hack things together, it will make it harder for you in the future. While I mostly agree, it isn't necessarily bad to have certain values represent a certain state or a generic value. For example, -1 representing wildcards or just "All", or having a date value of 2999-01-01 being "No expiry" or something. Important thing is to have a standard, so there isn't ambiguity for anyone else dealing with the system. And of course not to use values that would actually overlap with entries using them at face value. Which also means that your chosen values should be obvious to any observer that it's an intentionally out-of-norm entry. Comes with it's own pitfalls, of course, but sometimes there are reasons not to overload things with flags and additional data overhead. Which all loops around to the general idea of: plan your shit. It is generally a bad idea to use a single variable to express multiple things. Exceptions can be made if you're working in a low memory environment and such, but usually it is better to keep stuff separate until you run into a compelling reason not to. Otherwise: what can go wrong will go wrong.
But sometimes you can also structure parts of data in a way that one set bit provides 2 or more bits of information. It's pretty situational but when you come across it you can't help but feel amazed by it (that is, if it's implemented right and there's no ambiguity about it). It's similar to the old puzzle with scales and 12 identical-looking coins. One of the coins is either lighter or heavier than the others and you have to find out which one it is. You can put as many coins on each arm of the scale as you want but you can't use it more than 3 times before providing a solution.
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On September 15 2016 03:55 spinesheath wrote:Show nested quote +On September 15 2016 03:49 WolfintheSheep wrote:On September 15 2016 02:41 RoomOfMush wrote:On September 14 2016 07:40 travis wrote:
there will be multiple search terms, and I don't know what they are, so I can't set it to another string
I know I can set it to null, I was just wondering if there was a better option - is empty string a thing? If you want to solve your problem you should not try to find some kind of hack which incidentally does what you need, instead, simply solve your problem. You have a data structure which contains a number of data elements. You want to be able to set data elements to be temporarily invalid. Change your data structure or your data elements to allow this. For example, instead of storing Strings directly in your list, store instances of a class which themselves have a reference to a string and a boolean field which tells you whether this data element is invalid or not. Do not try to hack things together, it will make it harder for you in the future. While I mostly agree, it isn't necessarily bad to have certain values represent a certain state or a generic value. For example, -1 representing wildcards or just "All", or having a date value of 2999-01-01 being "No expiry" or something. Important thing is to have a standard, so there isn't ambiguity for anyone else dealing with the system. And of course not to use values that would actually overlap with entries using them at face value. Which also means that your chosen values should be obvious to any observer that it's an intentionally out-of-norm entry. Comes with it's own pitfalls, of course, but sometimes there are reasons not to overload things with flags and additional data overhead. Which all loops around to the general idea of: plan your shit. It is generally a bad idea to use a single variable to express multiple things. Exceptions can be made if you're working in a low memory environment and such, but usually it is better to keep stuff separate until you run into a compelling reason not to. Otherwise: what can go wrong will go wrong.
And forgetting to set or unset your flag variable is something that can go just as wrong as using null or -1 to mean it has not been correctly initialized. If you want to distinguish between too many things, I agree, but designating a basket to mean "invalid" is a really common practice, and one I generally agree with..
Code needs to be legible, and adding hundreds of flags is not necessarily the best way of doing that.
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is it normal to separate code into methods specifically for organization purposes? even if you are only using the methods once?
I keep failing to make my program, and part of the problem is it feels like I keep trying to fix problems with how my code works and it slowly gets more bloated and then it's super difficult to follow
but if I separated it into methods maybe it would make it easier to follow because it would make it easier for me to have a good idea of what each chunk of code is doing/supposed to do without studying it
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On September 15 2016 10:51 travis wrote:
is it normal to separate code into methods specifically for organization purposes? even if you are only using the methods once?
I keep failing to make my program, and part of the problem is it feels like I keep trying to fix problems with how my code works and it slowly gets more bloated and then it's super difficult to follow
but if I separated it into methods maybe it would make it easier to follow because it would make it easier for me to have a good idea of what each chunk of code is doing/supposed to do without studying it
This is more or less the idea of SRP (Single Responsibility Principle). Make each method only do one thing (even if it's only called once), and then you can test that method to make sure it's doing that one thing correctly. Even if you're not doing TDD or testing, you can still more easily analyse a small piece of code in one method than a big fat method.
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On September 14 2016 17:34 Morfildur wrote:Show nested quote +On September 14 2016 11:15 Blisse wrote:Why can't you just remove the objects from the list if you know you don't need them? On September 12 2016 13:25 WarSame wrote:On September 12 2016 06:52 Blisse wrote:
Yeah, academic integrity policy is intentionally vague so that it's a lot easier on them when they provide proof. Generally it's fine as long as you're just talking about the solution and not given exact pseudo/code. All reasonable professors I've seen encourage discussion, just not discussion with code being written.
I've consulted TL for a bunch of things too.
Instead of giving the problem description, you should abstract it one step up. I know it's a bit harder to do since you're starting out, but asking, "how do you find the smallest range of numbers in a list that contains a given set of numbers?" gives essentially the same solutions, and as long as no one is writing out a program for you, it should be fine asking for help.
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Actually it's kind of annoying/interesting that a lot of programming questions essentially rely on tricks that you need to learn first before you can actually solve them. Using sets and dictionaries IMO don't come intuitively, but instead from me reading advice that they're generally how to best solve a problem, and then I base my thinking with that in mind. I think the extreme example is being asked to find a loop in a linked list. No way you can reason yourself to a solution. I mean, I'm not particularly good, but couldn't you just put the pointer values of each node in a dict when visited, and if you come to a node already in the dict, then you've got a loop? How would you approach the problem if you couldn't hash the objects because the list is huge? + Show Spoiler [hint] + Pointers are tiny, so even a list with a million entries will have pretty much insignificant memory impact compared to the list and data itself, so a simple dictionary solution would still be pretty easy and probably faster, too, since you can abort on the first duplicate node. With the tortoise and hare solution you have to cross the distance that the slower pointer completed already, which means in a completely circular list you pretty much have to check 1.5n elements. The slower pointer crosses half the distance in the time for one complete loop, so now the faster pointer has to move around again until it reaches the slower pointer which is half the loop ahead. You can increase the speed at which the faster pointer moves, but then you'll be slower for partial loops that the faster pointer will circle around multiple times before the slower even enters them. In any case, the situation is completely academic since you should never have to check in code whether a list is circular or not. You should never actually interact with the nodes directly, only the data they contain, which means that you couldn't even be able to create any loops in a non-circular list if you wanted to. If you create your own linked list implementation then your code shouldn't allow for the possibility of a loop when you don't want one and making such a potentially expensive check at runtime inside a library is generally a bad idea.
Just to note... in an interview question you'll be simplifying many things. E.g. in this case they make the data structure a list so it's easier to deal with, because that's not the important thing you're dealing with. In reality it might be some other structure that you want to check for a loop.
Depending on where you end up working, you may need to deal with many things that don't fit in memory on a single machine (or any affordable set of machines). The data may have problems you'd need to figure out - a loop is a simple example.
The point is, if you threw a real work problem at someone in an interview setting and tried to have them solve it, you'd never hire anyone.
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Russian Federation4235 Posts
On September 15 2016 10:51 travis wrote:
is it normal to separate code into methods specifically for organization purposes? even if you are only using the methods once?
I keep failing to make my program, and part of the problem is it feels like I keep trying to fix problems with how my code works and it slowly gets more bloated and then it's super difficult to follow
but if I separated it into methods maybe it would make it easier to follow because it would make it easier for me to have a good idea of what each chunk of code is doing/supposed to do without studying it
Well, sometimes "god functions" are inevitable because not all things actual code does are easily separable into distinct steps and sometimes you need to do something complex that involves hundreds of lines of code and no idea on even how to name those separate steps should you figure them out. But it's still worth it at least for the reason of limiting the lifetime of local variables. It's much easier to reason about a piece of code when you have solid proof that any variables involved only exist in the span of the current screen and your changes can not have any effect on code you don't see. If having trouble naming, you can achieve the same by creating custom anonymous scopes within your god functions, but that's not possible in certain languages. I prefer nested scopes to separate methods when they're not easily named because reading code like "calculate_X_part_4(input, results_of_parts_1-3);" is even worse than 700-line "calculate_X(input);". Otherwise, when you see a standalone piece of code with a comment on what it does right above, go for it and make the comment into a method name.
Also, in C++ you can either explicitly inline those functions or rely on compilers detecting the "only called once" pattern and inlining them automatically, meaning zero overhead. Just make sure they are not exposed to the outside world as a part of some public interface.
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On September 15 2016 08:30 Acrofales wrote:Show nested quote +On September 15 2016 03:55 spinesheath wrote:On September 15 2016 03:49 WolfintheSheep wrote:On September 15 2016 02:41 RoomOfMush wrote:On September 14 2016 07:40 travis wrote:
there will be multiple search terms, and I don't know what they are, so I can't set it to another string
I know I can set it to null, I was just wondering if there was a better option - is empty string a thing? If you want to solve your problem you should not try to find some kind of hack which incidentally does what you need, instead, simply solve your problem. You have a data structure which contains a number of data elements. You want to be able to set data elements to be temporarily invalid. Change your data structure or your data elements to allow this. For example, instead of storing Strings directly in your list, store instances of a class which themselves have a reference to a string and a boolean field which tells you whether this data element is invalid or not. Do not try to hack things together, it will make it harder for you in the future. While I mostly agree, it isn't necessarily bad to have certain values represent a certain state or a generic value. For example, -1 representing wildcards or just "All", or having a date value of 2999-01-01 being "No expiry" or something. Important thing is to have a standard, so there isn't ambiguity for anyone else dealing with the system. And of course not to use values that would actually overlap with entries using them at face value. Which also means that your chosen values should be obvious to any observer that it's an intentionally out-of-norm entry. Comes with it's own pitfalls, of course, but sometimes there are reasons not to overload things with flags and additional data overhead. Which all loops around to the general idea of: plan your shit. It is generally a bad idea to use a single variable to express multiple things. Exceptions can be made if you're working in a low memory environment and such, but usually it is better to keep stuff separate until you run into a compelling reason not to. Otherwise: what can go wrong will go wrong. And forgetting to set or unset your flag variable is something that can go just as wrong as using null or -1 to mean it has not been correctly initialized. If you want to distinguish between too many things, I agree, but designating a basket to mean "invalid" is a really common practice, and one I generally agree with.. Code needs to be legible, and adding hundreds of flags is not necessarily the best way of doing that.
Additional flags are not the only way to deal with such things. Most of the time when you would need a flag - or a special value that has the same meaning - and consequently an if or switch that checks the flag (often in multiple places), there is a clean polymorphic solution hidden in somewhere. Like a null object for example.
On September 15 2016 19:17 BluzMan wrote:
Well, sometimes "god functions" are inevitable because not all things actual code does are easily separable into distinct steps and sometimes you need to do something complex that involves hundreds of lines of code and no idea on even how to name those separate steps should you figure them out..
While it might be true that sometimes a problem has a certain inherent complexity that forces longer functions, I would argue that these are extremely rare. Hundreds of lines is clearly excessive and you never should accept that kind of code as inevitable. A nice solution might not present itself right away, but if you can come back after a while and have another go at breaking it down, you probably will get a step closer.
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On September 16 2016 02:24 spinesheath wrote:Show nested quote +On September 15 2016 19:17 BluzMan wrote:
Well, sometimes "god functions" are inevitable because not all things actual code does are easily separable into distinct steps and sometimes you need to do something complex that involves hundreds of lines of code and no idea on even how to name those separate steps should you figure them out.. While it might be true that sometimes a problem has a certain inherent complexity that forces longer functions, I would argue that these are extremely rare. Hundreds of lines is clearly excessive and you never should accept that kind of code as inevitable. A nice solution might not present itself right away, but if you can come back after a while and have another go at breaking it down, you probably will get a step closer.
Past 2 years of my life in a nutshell... Most of the time I'm doing tasks that others find too ungrateful/hard to do, which for the most part involves fixing 10 year old code with functions that span thousands of lines of code.
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Tip of the day: In SQLite databases don't make id UNSIGNED. It'll disable the autoincrement...
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I want to code something up, probably in PHP unless the arguments to use Ruby are particularly compelling. What's a good unit testing framework for PHP?
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28096 Posts
Isn't PHPUnit supposed to be ok. I don't do any PHP though so I could be incredibly wrong 
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Hyrule19192 Posts
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What does "generic notation" mean?
context: my java class gave us a small assignment. part of the assignment needs my class to implement the comparable interface. and then it says, "don't forget to use generic notation".
what does generic notation actually mean
is this just fancy terminology for when you label something, say arraylist, with the object type? like: Arraylist<bullshitobject> ?
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On September 17 2016 13:22 Birdie wrote:
I want to code something up, probably in PHP unless the arguments to use Ruby are particularly compelling. What's a good unit testing framework for PHP?
PHPUnit for unit testing. Behat for BDD.
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On September 20 2016 05:11 travis wrote:
What does "generic notation" mean?
context: my java class gave us a small assignment. part of the assignment needs my class to implement the comparable interface. and then it says, "don't forget to use generic notation".
what does generic notation actually mean
is this just fancy terminology for when you label something, say arraylist, with the object type? like: Arraylist<bullshitobject> ?
In ArrayList<T>, T is a generic parameter that could be any type, and ArrayList<T> is a generic class. Nothing fancy about the word "generic", though I don't usually see the word "notation" thrown in. So I suppose that's what they are after. Sometimes you restrict generic parameters to subclasses of certain types or require them to implement certain interfaces. For example a SortedList<T> would probably require T to implement the Comparable interface.
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Whoops, Quote instead of Edit.
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I am still a little confused
What we are doing is writing a class called hurricane
in it we implement Comparable
then we write a compareTo method, and an equals method
the goal of course being to compare hurricanes (by default, we are comparing them by "windspeed" ints)
Now it would seem to me that I would be doing:
public Class Hurricane implements Comparable<Hurricane> {
...
...
public int compareTo(Hurricane other) {
....
...
}}
but are you saying that they want:
public Class Hurricane implements Comparable<T> {
...
public int compareTo(Object other) {
...
?
edit: no... that would make no sense
compareTo must take hurricanes
so I don't get what they are asking for
edit 2: maybe they want me to cast the object to type hurricane?
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EPT
