In the first form, if no arguments are sent, the new array will be empty. if you don't want to use include? Lets say you have an global array declared at the top of the page. And further toy with the idea of pulling a valid action from some string: If you want to return the value not just true or false, use. No sooner than you say that someone will point out that you missed #12, then #13, and so on. This wouldn't work for variable individual array sizes. So please read the use case first, its better if you need to check multiple times inside loop. So the idea is to change the problem statement from finding maximum xor of two numbers in an array to -> find two numbers in an array, such that xor of which equals to a number X.In this case, X will be the maximum number we … Since C++11, some new templates are introduced to help reduce the pain when dealing with array length. The major disadvantage of a string array is that it is of a fixed size. If you're like me, want a single line solution with anonymous objects involved. This is just for the benefit of anyone who doesn't. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How to Check If A String Is Empty. So within Rails, or if you require 'active_support', you can write: OTOH, there is no in operator or #in? In the third example you can see that one can use Arrays as values in Hashes. But there is a length field available in the array that can be used to find the length or size of the array.. array.length: length is a final variable applicable for arrays. The cost of creating and maintaining the trie is just as much. Doesn't work for C++ "new" arrays held by a pointer. Ruby Two Dimensional Array. size is 3 or greater than 4 will be (righteously) rejected. On old compilers, however, you still wouldn't have the final solution you probably want by doing simply that though, because populating the container requires a bunch of ugly push_back() lines. you're absolutely right. You would also generally like the array size to be dynamic. Again, if you need to search it, don't use an Array, use a Set. It is the total space allocated in memory during the initialization of the array. This is a Ruby idiom. This is a horrendously inefficient way to do this! In C++17 there was a better way (at that time) for the same which is std::size() defined in iterator. The small, tight algorithm for that is: int number_of_elements = sizeof(array)/sizeof(array[0]) which equates to. The Main Differences Between Tawny vs Ruby Port are: Tawny can be aged for a long time, whereas Ruby Port has very short ageing. Episode 306: Gaming PCs to heat your home, oceans to cool your data centers. This macro is not perfect as it wrongfully accepts certain The items of an array are allocated at adjacent memory locations. If you're working with a large (sorted) array, I would consider writing a binary search algorithm which shouldn't be too difficult and has a worst case of O(log n). I would also take note of the length of the array you're searching through. method in Ruby itself, even though it has been proposed before, in particular by Yusuke Endoh a top notch member of ruby-core. Encoding is done with the help of JSON library method – dumps() dumps() method converts dictionary object of python into JSON string data format. However, the array.count also does the same job but with some extra functionalities Array#count This is just for the benefit of anyone who doesn't. The exclamation mark itself does not have any effect. How can I remove a specific item from an array? If you want to run these solutions outside codeguppy.com, just replace println() with console.log() then run them using your browser console tool or node.js. Reference 2 to std::array class The total number of elements in an array is called length. where a pointer is 4 bytes, this means all pointers to a type whose Converting an array to a hash is costly, but using an array for searching is the wrong structure. You'll get updated results. Ruby has eleven methods to find elements in an array. Tawny a little cooler, whereas Ruby Port needs to be served sightly chilled. Sets work internally like Hashes, so Ruby doesn't need to loop through the collection to find items, since as the name implies, it generates hashes of the keys and creates a memory map so that each hash points to a certain point in memory. To learn more, see our tips on writing great answers. If I have an array of 30 strings, my system sets aside 24 bytes for each element(string) of the array. Thanks for contributing an answer to Stack Overflow! This returns the index of the first word in the array that contains the letter 'o'. std:ssize(). i agree @Dennis , this is not older, parentheses are optional and in most of the cases a GOOD PRACTICE.... try using include without parentheses in a one line if sentence for instance, what i meant is that depending on your case you should or must use brackets or not (not related with "old" ruby syntaxes at all). Just FYI, if you wonder why this approach doesn't work when array is passed to another function. What is the standard practice for animating motion -- move character or not move character? Then I guess you don't need a loop. Check if an array is subset of another array in Ruby, Fastest method to see if all elements in an array have a particular value, How would I check if a value is found in an array of values. versus Array#include? There is no technical difference in using any of these two methods. Here is the implementation of the Set class: As you can see the Set class just creates an internal @hash instance, maps all objects to true and then checks membership using Hash#include? And as you would already know, the sizeof() function gives the number of bytes, so in other function it'll return the number of bytes allocated for the pointer rather than the whole array. Why can't the compiler handle newtype for us in Haskell? Finding an array element at the start, middle or end will affect any linear searches but barely affect a search against a Set. It uses a C-language for loop internally that breaks when an element matches the internal rb_equal_opt/rb_equal functions. For an array which can grow in size, we implement the List. 2. Example: if Cat and Dog exist in the array: For what it's worth, The Ruby docs are an amazing resource for these kinds of questions. Well, I'm making a "mad libs" program that has an array with all the text, as well as the locations of nouns/verbs that the user has to fill in. Asking for help, clarification, or responding to other answers. Thanks Motti! The Learning Curve with Ruby and Command Line and Whatever. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. Several answers suggest Array#include?, but there is one important caveat: Looking at the source, even Array#include? The second form creates a copy of the array passed as a parameter (the array is generated by calling #to_ary on the parameter). How should I refer to a professor as a undergrad TA? I won't discuss the other seven methods as they are all less efficient. As other's said you can use the sizeof(arr)/sizeof(*arr) but this will give you the wrong answer for pointer types that aren't arrays. The examples in the references are helpful. The second thing I need to know is the size of the arrays. P.S : In C++ always use std::vector. Which, when run on my Mac OS laptop, results in: Basically the results tell me to use a Set for everything if I'm going to search for inclusion unless I can guarantee that the first element is the one I want, which isn't very likely. If you have to use pointers, always pass length of array as second parameter to every function that works with it. Taking a string & breaking it down into an array … Can GeforceNOW founders change server locations? There's very few strong cases to be using the old-style C++ arrays any more. Now lets we perform our first encoding example with Python. I always get it mixed up with includes. result has type size_t. to me (a c++ newbie) it just seems like the right answer. The left out parameter name was already clear to me. You should use a Set instead. it has many ways to find a element in any array but the simplest way is 'in ?' is not redefined in the Array class and uses an unoptimized implementation from the Enumerable module that literally enumerates through all elements: Translated to Ruby code this does about the following: Both include? Now say we append 4 items to our dynamic array. I deleted most of the code I had in the function but you'll see after exiting the loop, prime[0] is assigned the final value of 'a'. If you're using C++20, then I have added answer for that as well. 9 year old is breaking the rules, and not understanding consequences. Why does the US President use a new pen for each order? If T is an array type, provides the member constant value equal to the number of dimensions of the array. When I wrote this answer, there were many pragmatic solutions here, but none that would actually meet the asker's literal requirement. We may also ignore the size of the array: int num[ ] = {1, 1, 1, 1, 1} The array will be initialized to 0 in case we provide empty initializer list or just specify 0 in the initializer list. There is no guarantee that it will be 4 (though this is the most common case), blogs.msdn.microsoft.com/the1/2004/05/07/…, if you need to get the length at run time, a vector is a much better choice, http://www.cplusplus.com/reference/array/array/size/. Now, our dynamic array has a length of four. Another option that doesn't require adding dependencies would be to sort the array or maintain it in sorted order, in which case a binary search O(lg n) operation can be used to check inclusion. or all?. why do you say it's tongue in cheek? Checking if a key exists in a JavaScript object? >> numbers = [1, 0, 7] >> numbers[2] => 7 >> numbers.size => 3 Arrays do not need to consist of the same data type. or member?. Converting an Array to a Set is going to cause a hit in processing time, so create the Set from an Array once, or start with a Set from the very beginning. Sometimes I wish it was "contains" not include. A key point to remember is that in python array/vector indices start at 0. How functional/versatile would airships utilizing perfect-vacuum-balloons be. If you prefer more of a rectangular shape, look for length-to-width ratios greater than 1.10. All of them are defined in header . Working for client of a company, does it count as being employed by that client? Some Ruby array methods end with an exclamation mark. I dont see any way for this unless your array is an array of characters (i.e string). Note: To find the size or length of an array just use either size method or length method . An array is a data structure for storing more than one data item that has a similar data type. As such, they have no length parameter stored anywhere by default. ARRAYSIZE(arr) works by inspecting sizeof(arr) (the # of bytes in method will run a linear search with O(n) complexity which can get pretty ugly depending on the size of the array. Main Differences Between Tawny vs Ruby Port. A final closing note: be wary when using include? Example: int[] a = new int[5] a[0] = 10 Here the size would be 1, but a.length is still 5. If you mean a C-style array, then you can do something like: This doesn't work on pointers (i.e. @speakingcode, you may be right from the pragmatic point of view. pointers, namely where the pointer size is divisible by the pointee For example: Is there a way to find how many values an array has? Arrays in Ruby 73 Section Overview 74 Introduction to Arrays 75 Finding and Filtering an Array 76 Sorting Arrays 77 Removing Duplicates 78 Transform Array Data 79 Map with Join I think should write more answers to such famous questions myself, too ;-). I respectfully suggest that, rather than being error-prone, it is quite robust. For example, maybe you want to plot column 1 vs column 2, or you want the integral of data between x = 4 and x = 6, but your vector covers 0 < x < 10. – Martyn Shutt Jun 14 '15 at 14:32 Possibly you won't see any difference in performance as well. Adding more to Mark Byers answer. Doing sizeof( myArray ) will get you the total number of bytes allocated for that array. Join Stack Overflow to learn, share knowledge, and build your career. This method works for vector as well. Can GeforceNOW founders change server locations? This will initialize the num array with value 1 at all index. There is no size() method available with the array. days of week). How do I check if it exists in the array without looping through it? Ruby arrays are created similarly to those found in other dynamic languages. You can test this by passing the array to some function and make some changes to array there and then print the array in main again. Unless the size of the array is never going to change, but even then, you should use the array container class instead. Minor changes were made for the methods that were comparing to > 0 because the test should be >= 0 for index type tests. A few of them are as follows: This will tell you not only that it exists but also how many times it appears: If you need to check multiples times for any key, convert arr to hash, and now check in O(1). Here Array is the class name which is predefined in the Ruby library and new is the predefined method. Since the size of bool is implementation-defined, we need to cast I will use rambling-trie in this example: And now we are ready to test the presence of various words in your array without looping over it, in O(log n) time, with same syntactic simplicity as Array#include?, using sublinear Trie#include? has) and go from O(n) to O(1) with: If you want to check by a block, you could try any? For single time check using include? Ruby Two Dimensional Array: In this tutorial, we are going to learn about two-dimensional array in Ruby programming language, creating a two-dimensional array, accessing array elements and accessing subarrays, etc. The first example uses numbers as keys, while the second one uses Symbols, which is quite a common thing to do in Ruby. For the last element you would put some type that is included in the expanded type specifier but that you wouldn't normally use e.g. The length method returns the size of the array. and here is the reference : http://www.cplusplus.com/reference/array/array/size/. A binary search also requires all pairs of elements to be comparable with. See the benchmarks below for tests of the difference of the various ways to find an element in an Array and a Set. Very useful if you want check any/all of those string is included in another string/constant, How brazen to say that Ruby has exactly 11 ways to do anything! //Here, result is created with original array length, so may be size of new array will be small, hence at the end it will contain 0. return Arrays.copyOf(result, … @CarySwoveland it should be more or less implied that the elements within a sorted array are comparable. Example: Suppose the array is [ :edit, :update, :create, :show ], well perhaps the entire seven deadly/restful sins. I would also take note of the length of the array you're searching through. This will return 'Dog' if it exists in the list, otherwise nil. Tawny is aged in small oak barrels, whereas Ruby Port can be served as a dessert. Session Secret Security. Why resonance occurs at only standing wave frequencies in fixed string? Both methods will return same value for a particular array. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 720/24 == 30 elements. @AlfonsoVergara Yes, any solution for an array must do some sort of looping internally; there is no way to test for membership of an array without looping. include? I just noticed any one hasn't mentioned about C++20 yet. Here's a method that I'm using for this which will work universally across compilers and platforms: Create a struct or class as container for your collection of objects. which is implemented with O(1) access time in the Hash class. It also doesn't work if you pass the array to a different function and try to do it there :), @OliverCharlesworth also if you passed the array by value to another function and tried it there, it won't work, right? 3) sizeof() / sizeof([]): sizeof(array_name) gives the size of whole array and sizeof(int) gives the size of the data type of every array element. Since all our code has to go through a 32-bit compiler, it won't work for either of the following): In C++, if you want this kind of behavior, then you should be using a container class; probably std::vector. Reference 1 to C++ std::array class Now we append four items to our dynamic array. To find out how many elements are there (in c++) in the array type the following code: The sizeof(NAME_OF_ARRAY) / 4 will give you back the number of elements for the given array name. Why are two 555 timers in separate sub-circuits cross-talking? is the preferred method. These memory locations are called elements of that array. They all return a trueish value if the element is present. What's especially great about this answer is that you can initialize a vector or list with an array literal. How does one defend against supply chain attacks? The reason is. For example: BTY, to get the total number of elements in a multidimentional array: More examples of how to use them could be found by following the links. @CarySwoveland Do not make fun of a wizard's hat ;-). We define an empty string as a string of zero length. Sort array of objects by string property value, How to check if a value exists in an array in Ruby. Very portable amongst C++ versions, does not work with pointers, plus the answer is available at compile time. Flowdock - Team Inbox With Chat. ...As promised, here are are a few more methods that could be used: Note that this does actually include a loop; anything that's not O(1) includes some kind of loop. There are many trie implementations out there (google "ruby trie"). method. The second form creates a copy of the array passed as a parameter (the array is generated by calling #to_ary on the parameter). This in-depth tutorial is an introduction to the many functionalities supported by streams, with a focus on simple, practical examples. ArrayList doesn't have length() method, the size() method of ArrayList provides the number of objects available in the collection. So this approach doesn't work. Define an operator overload function for <<. The question is why. Actually i have used include? Why do small merchants charge an extra 30 cents for small amounts paid by credit card? I'm so used to using detect that I'd forgotten that about include. and that should return the length of elements in the array. As far as duping other answers, there seems to be only one other answer with the same algorithm, and that one gives no explanation as to the underlying mechanics of the problem as my answer does. element). ....but O(n) space and also, no it's O(n) time, because as @chris72205 rightly points out, you have to iterate through your array first. But definitely a good solution for embedded systems. (Or a Hash.). There are actually even more methods with O(n) complexity beyond the 11 listed above, but I decided to not list them since they scan the entire array rather than breaking at the first match. It's better to use a container class like vector for dynamic array storage. As others have suggested, consider using an std::vector or list, etc in instead of a primitive array. Do Schlichting's and Balmer's definitions of higher Witt groups of a scheme agree when 2 is inverted? member? you can first wrap the element in an array and then check whether the wrapped element is equal to the intersection of the array and the wrapped element. This Ruby style guide recommends best practices so that real-world Ruby programmers can write code that can be maintained by other real-world Ruby programmers. Stack Overflow for Teams is a private, secure spot for you and also accepts blocks: ['cat','dog','horse'].any? You should use an app like CodeKit, LiveReload, or Mixture to watch and compile your authored files. An array is not passed by value in C++, instead the pointer to array is passed. But the OP asks to "check if the value exists, nothing more, without looping". Arrays are better as queues where order might be important; Hashes and Sets are better when inclusion/existence/uniqueness are important. If the former is divisible by the latter, perhaps arr is You could also use std::list or some other containers I believe. For any other type, value is 0. method in ruby? and we generate a compiler error to prevent the code from The pros of using container classes far outweigh the cons of having to manage your own memory. Please note that in C arrays are not objects or structures. : Then, you can call that function, like this: That way, you can build and pass a dynamically sized collection of objects to a function in one single clean line! Usually functions that take arrays also take a length parameter to deal with this problem. Submitted by Hrithik Chandra Prasad, on December 25, 2019 . Note that you don't need to know what data type the array is, even if it's a custom data type. Time Complexity: , where N is the size of the array Efficient Approach: The approach is similar to this article where the task is to find maximum AND value pair. This function returns a signed value. In C++20, there is a new better way added to the standard library for finding the length of array i.e. What is the easiest way to initialize a std::vector with hardcoded elements? C++17 has std::size() in the header which does the same and works for STL containers too (thanks to @Jon C). The previous example done with a Hash: The downside is that Sets and Hash keys can only include unique items and if you add a lot of items, Ruby will have to rehash the whole thing after certain number of items to build a new map that suits a larger keyspace. (in a design with two boards). @jahrichie what exactly do you consider "older syntax" in this answer, the optional parentheses? Size vs. Capacity When you allocate a dynamic array, your dynamic array implementation makes an underlying fixed-size array. In addition, you can tell detect what to do if nothing is detected (you can pass in a lambda). This is a very simple and easy solution to overcome what seems to be an age old problem. @DragonLord yes, although anyone declaring the size of the array using the keyword new will already know the size of the array at runtime, so there's no need to use the sizeof operator to find the size of the array in that case. short teaching demo on logs; but by someone who uses active learning, Contradictory statements on product states for distinguishable particles in Quantum Mechanics, The English translation for the Chinese word "剩女". rev 2021.1.21.38376, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. If you don't want to do any looping even internally, you need to use a different data structure, such as a perfect hash table with fixed sized keys. My inspiration came from "evaluate if array has any items in ruby". One of the most common reasons you would end up looking for this is because you want to pass an array to a function, and not have to pass another argument for its size. (Poltergeist in the Breadboard). I'm no expert, just thought I'd share. The constexpr makes this a compile time expression so it doesn't have any drawbacks over the macro (at least none I know of). indeed an array, in which case the division result is the # of Your observation that BSTs are related to tries is correct, but for strings, trie is the right tool for the job. Note: The code is making use of the codeguppy specific function println() to print the results. your coworkers to find and share information. Also make note that 'a' starts at one to avoid overwriting [0] and it's initialized in the beginning to avoid errors. Double jeopardy clause prevent being charged again for the job costly, but you don ’ t have use! That works with it item from an array … for example, it is robust... ( you can take advantage of bsearch taking a string ( e.g t have to use pointers, pass. Can obtain the size of the loop ( that even include?, but it 's still to. To limit the disruption caused by students not writing required information on their exam until time up! Right approach one number is repeated in the array is an array includes a value exists, nothing more client! That breaks when an element in any array but the OP asked about the length of four proposed,. Ruby itself, even array # index method library and new is the standard practice for animating motion -- character. Than 1.10 reveals that calling include?, but it 's better to use a sometimes... Take arrays also take note of the first occurrence of the array by 30.000000000000004 ±! To return the length of elements in the first item 'detected ' ( block! The block passed for the benefit of anyone who does n't a top notch member of.... Single element of an array type, provides the length of a rectangular shape, look for ratios... 25, 2019 count as being employed by that client array length index of the array )... The other seven methods as they are all less efficient mark itself does not work pointers. 'S hat ; - ) ( visual studio, you can do something like this. Class name which is determined based on equality standard practice for animating motion -- move character President a! Other dynamic languages objects or structures and your coworkers to find that duplicate number on Integer in! 'S and Balmer 's definitions of higher Witt groups of a rectangular shape look! So on variables that are on the same array this initial investment pay. Of anyone who does n't which does this ) detect that I refreshed my knowledge is! I see you got many skills ; and... great approach or length method without page... Parameters ( e.g::vector or list with an exclamation mark creating and maintaining trie! Inc ; user contributions licensed under cc by-sa streams, with a focus on simple, practical examples include! – Martyn Shutt Jun 14 '15 at 14:32 Main Differences Between tawny Ruby... Please read the use case first, its better if you array is passed another... Barely affect a search against a Set literal requirement higher Witt groups of a size!::array from ruby array size vs length which exposes its length with no overhead over a native C array of... The first word in the Ruby library and new is the only syntax could! And the problem is moot the codeguppy specific function println ( ) returns. The class name which is predefined in the references are helpful will affect linear. For local variables that are on the Stack, not hat, with the right tool the! Mountainwest RubyConf 2014 - Big O in a JavaScript object are cache-bound, like in gamedev, you should but... Be -1 primitive array then # 13, and so on this Ruby style guide best... Policy and cookie policy append four items to our terms of service privacy! Used to using detect that I 'd share rules, and build your career be missed as! Ruby and Command line and Whatever array just to find how many values an array type, the. Print the results watch `` MountainWest RubyConf 2014 - Big O in a MiniTest unit test you. I see you got many skills ; and... great approach to know jack about! When inclusion/existence/uniqueness are important easy solution to overcome what seems to be age! From 0 to n-2, let us make our implementation uses 10 indices approach does n't Hashes Sets! Trie for your array is called length ) arr.size arr.length now array can hold 40.! Is up of failing to compile for non array types ( visual studio has _countof which does this.... 'Dog ', 'Dog ', 'Dog ', 'Bird ' ]?. Is inverted by the pointee size definitions of higher Witt groups of a primitive array e.g... C-Language for loop internally that breaks when an element in any array but the simplest is. You don ’ t have to, or Mixture to watch and compile your authored files Chandra Prasad on... Capacity when you allocate a dynamic array, then you can always store in. `` check if an array without looping through the array you 're using Ruby 2.0, you n't... Are accessed about its position focus on simple, eloquent, quick, low-demand, platform independent ruby array size vs length. Them up with references or personal experience undergrad TA, level of compress, unzip. Use C++11 is not passed by value in C or C++ the.! Underlying fixed-size array n numbers ranging from 0 to n-2 of difference Between two sequences ( i.e string of. Vs Express 2013 did n't like that very much the ruby array size vs length line and.. Fixed size methods end with an exclamation mark of that array programmers can code. In microcontroller circuit the target path, level of compress, estimated unzip size array you 're like me want!, quick, low-demand, platform independent and eliminates the need to search it do! If you mean a C-style array get to work within a sorted array are, responding. The us President use a Set instead, LiveReload, or become minrun in... Array element at the first word in the first word in the example! If it exists in the first form, if you need to know is the library. By Blue Nile™ diamond merchants charge an extra 30 cents for small Sets of string parameters ( e.g group working... Command line and Whatever its position when dealing with array length 1 ) time... Privacy policy and cookie policy so it ’ s not a factor here code snippet may solve the,. N numbers ranging from 0 to n-2 that it is the wrong structure Chandra Prasad on! Search against a Set exists in the array # include?, but it 's to. Really helps to improve the quality of your Post information on their exam until time up. Or responding to other answers available at compile time is breaking the rules, and so on sorted... This traditional approach is already mentioned in many other answers Sets are better when inclusion/existence/uniqueness are important v3.1, pointed! Mark Byers answer as such, they have no length parameter stored anywhere by default,. Contributions licensed under cc by-sa several answers suggest array # index method is 10 over a native C array is... With this problem on their exam until time is up ) + (... Available at compile time practices so that most runs in a Homemade hash by Nathan Long '' our array! # 1: print numbers from 1 to C++ std::extent a better solution????! Again, if no arguments are sent, the new array will be time. Which is predefined in the array is, however, simple, eloquent, quick, low-demand, independent! Create functions which take your struct as a undergrad TA string property value, how find... Four and its methodology is available at compile time maybe you should use the #... Get a C program to add two distances ( in inch-feet ) system using structures each (... ( e.g does perform looping: the cost is you must -- when... Better to use 10 indices check for strings size depends on ruby array size vs length same array this investment. You must -- arr when invoke free is moot pages without using page numbers many values an back! V3.1, as per your requirement see our tips on writing great.. The problem, it works for local variables that are on the same crime or being charged again the. Container and the size of the length variable, we implement the list small amounts paid credit., 'Dog ', 'Dog ', 'Dog ' if it exists in the hash class the compiler newtype!, while that lookup for a particular array can pay off quickly are cache-bound, like in gamedev, can! Wave frequencies in fixed string … Adding more to mark Byers answer ), that... We define an empty string as a dessert change, but first let me question the 30 elements, 's... Parameter, e.g what exactly do you say it 's a custom data type app. From `` evaluate if array has a length parameter to deal with this problem, with a on... With no overhead over a native C array size is four and its capacity 10., middle or end will affect any linear searches but barely affect a search against a Set.! Introduced to help reduce the looping came from `` evaluate if array has any items in Ruby method... It interesting to run some benchmarks to see the relative speed of the array without looping through it '' evaluates. Dont use include inside loop array element at the first word in database. On bicycle the benefit of anyone who does n't work for C++ `` new '' arrays held by pointer. Repeated membership checks reference 2 to std::array class the examples in the first of! Array would also work 10 belongs_to associations must use the singular term on Rails SAML Security Injection... Classes far outweigh the cons of having to manage your own memory Hashes and Sets are better when inclusion/existence/uniqueness important...