comparison

问题 I need to compare a query bit sequence with a database of up to a million bit sequences. All bit sequences are 100 bits long. I need the lookup to be as fast as possible. Are there any packages out there for fast determination of the similarity between two bit sequences? --Edit-- The bit sequences are position sensitive. I have seen a possible algorithm on Bit Twiddling Hacks but if there is a ready made package that would be better. 回答1: If the database is rather static, you may want to

问题 I asked this question: static_assert of const Variable And apparently it comes down to the question does a floating point lvalue get converted to an rvalue for the purposes of comparison? So in this code does an lvalue-to-rvalue conversion occur? const float foo = 13.0F; static_assert(foo > 0.0F, "foo must be greater than 0."); 回答1: Yes, it is performed. Basically, it's all because 3.0 > 1.2 is a well-formed expression, that contains nothing but prvalues for operands. First, [expr]/9 states

问题 Why does String.IndexOf(String, StringComparison) require a StringComparison and not allow for the more general StringComparer , or even just IComparer<T> or IEqualityComparer<T> ? I made a custom StringComparer to use with several dictionaries, and I want to use it in other parts of my project but I can't find a good way to do that without making lots of extensions methods, if those would even work. This is the comparer I made. It was based roughly on this recommendation: Implementing custom

问题 What would be the smallest and largest number of comparisons in an unsorted array that could have duplicate elements as well ? I understand that finding anything in an unsorted array is a O(n) problem. But, is this true if the array contains duplicate elements as well ? By duplicate elements I mean, elements that occur more than once in the given array. 回答1: So the idea here is that you've got to walk the array from front to end because it is unsorted. That means you're looking at O(n) - a

问题 I've seen plenty of comparisons of Doctrine vs Propel, but none of them has actually convinced me to choose Doctrine over Propel. I've been using Propel for a while now and almost every comparison I read states that Propel is not well documented as the first problem and I've read Propel's docs and they're quite well. Also, most of comparisons are dated, (using Propel 1.5+). Does anyone knows of a highly convincing post in a blog where I can see test results and some actual differences? 回答1: I

问题 My problem, in a nutshell, is this: What can I do about storing a tuple (or any type with a constraint of 'comparison') in a C# container that requires an IComparable ? This works: > let x (y : 'a when 'a : comparison) = y ;; val x : y:'a -> 'a when 'a : comparison > x (1,2) ;; val it : int * int = (1, 2) I would have thought this would work: > let x (y : IComparable<int>) = y ;; val x : y:IComparable<int> -> IComparable<int> > x (1,2) ;; x (1,2) ;; ---^^^ stdin(28,4): error FS0001: The type

问题 I saw if($output !== false){ } It's an exclamation mark with two equals signs. It almost works like not equal. Does it has any extra significance? 回答1: They are the strict equality operators ( ===, !==) , the two operands must have the same type and value in order the result to be true. For example: var_dump(0 == "0"); // true var_dump("1" == "01"); // true var_dump("1" == true); // true var_dump(0 === "0"); // false var_dump("1" === "01"); // false var_dump("1" === true); // false More

问题 What are the key differences between Android, iOS and Blackberry OS in terms of level of accessibility by application developers (i.e. access to the video input, sound input, phone functionalities, to which extent, etc.)? PS: Assume latest version of each OS. EDIT: Can someone turn this into a wiki so we can compile answers from people that don"t necessarily have experience in all 3 plaforms. 回答1: I'm not familiar with BlackBerry, but on Android and iOS you can access just about anything.

问题 I need to access the internal binary representation of a loaded XML DOM... There are some dump functions, but I not see something like "binary buffer" (there are only "XML buffers"). My last objective is to compare byte-by-byte, the same document , before and after some black-box procedure , directly with their binary (current and cached) representations, without convertion (to XML-text representation)... So, the question, There are a binary representation (in-memory structures) in LibXML2,

问题 I'm working on a cryptography application ,using Crypto++ As an obscure part of this application, I need to determine the maximum number of unique float values that can exist within a certain numeric range. Obviously there are infinite numbers between 0 and 1 in reality - but not all of them can be represented by a unique float value. I have a minimum float value, and a maximum float value. I need to determine the number of possible float values inside this range. This is tricky, because