comparison

问题 I currently review an old C++ codebase and see a lot of code going like this: bool SomeClass::operator==( const SomeClass& other ) const { return member1 == other.member1 && member2 == other.member2; } bool SomeClass::operator!=( const SomeClass& other ) const { return member1 != other.member1 || member2 != other.member2; } clearly comparison logic is duplicated and the code above will likely have to be changed in two places instead of in one. AFAIK the typical way to implement operator!= is

问题 For enums with associated values, Swift doesn't provide the equality operator. So I implemented one to be able to compare two enums: enum ExampleEnum{ case Case1 case Case2(Int) case Case3(String) ... } func ==(lhs: ExampleEnum, rhs: ExampleEnum) -> Bool { switch(lhs, rhs){ case (.Case1, .Case1): return true case let (.Case2(l), .Case2(r)): return l == r case let (.Case3(l), .Case3(r)): return l == r ... default: return false } } My problem is that I have a lot of such enums with a lot of

问题 Does anyone know of a simple way to compare two strings together to generate the "amount of difference" between the two? (in a numeric value) I have been crawling google with little luck on this. And after doing some coding it's not as simple as I had thought. Any clues? 回答1: Are you talking about the "Edit Distance"? Do a search on "Levenshtein Distance", on SO or Google. I use the version posted on Stephen Toub's blog 回答2: You're looking for the Levenshtein distance. 回答3: You might want to

问题 I have the matrix: a = [ 1 2 3 4; 2 4 5 6; 4 6 8 9] and I want to compare every row with every other two rows one by one. If they share the same key then the result will tell they have a common key. 回答1: Here's one solution (which is generalizable to larger matrices than the sample in the question): comparisons = nchoosek(1:size(a,1),2); N = size(comparisons,1); keys = cell(N,1); for i = 1:N keys{i} = intersect(a(comparisons(i,1),:),a(comparisons(i,2),:)); end The function NCHOOSEK is used to

问题 i am comparing updates to two strings. i did a: string1 != string2 and they turn out different. I put them in the "Add Watch" and i see the only difference is one has line breaks and the other doesnt'.: string1 = "This is a test. \nThis is a test"; string2 = "This is a test. This is a test"; i basically want to do a compare but dont include line breaks. So if line break is the only difference then consider them equal. 回答1: A quick and dirty way, when performance isn't much of an issue:

问题 I'm in the process of normalising a database, and part of this involves converting a column from one table from a FLOAT to a DECIMAL(28,18) . When I then try to join this converted column back to the source column, it returns no results in some cases. It seems to bee something to do with the ways its converted. For example, the FLOAT converted to a DECIMAL(28,18) produces: 51.051643260000006000 The original FLOAT is 51.05164326 I have tried various ways of modifying the FLOAT , and none of

问题 I have a few float s which I convert to NSNumber s and add to an array, then sort in numerical order. I then take the original float s and convert those to NSNumber s, but if I try to compare them if(numinarray = newnum){ it never goes anywhere. When I NSLog() out the value, the values match: float distance = [barnardCastle distanceFromLocation:loc1] / 1000; float distance2 = [billingham distanceFromLocation:loc1] / 1000; float distance3 = [bishopAukland distanceFromLocation:loc1] / 1000;

问题 Following Arthur's suggestion, I changed my Fixpoint relation to a mutual Inductive relation which "builds up" the different comparisons between games rather than "drilling down". But now I am receiving an entirely new error message: Error: Parameters should be syntactically the same for each inductive type. I think the error message is saying that I need the same exact parameters for all of these mutual inductive definitions. I realize there are simple hacks to get around this (unused dummy

问题 I'm doing a fairly exhaustive series of DOM manipulations where a few elements (specifically form elements) have some events. I am dynamically creating (actually cloning from a source element) several <select> boxes and assigning a change() event to them. The change event executes, and within the context of the event, "this" is the HTML Element Object. What I need to do at this point however is determine a context for this HTML Element Object. I have these objects stored already as jQuery

问题 Does anyone know about a way in java to compare a handwritten text sample (e.g. a signature, autograph etc) to one or more samples? Preferably open-source? 回答1: You can check out this OCR Applet. 来源： https://stackoverflow.com/questions/13109435/handwritten-signature-comparison