indexing

问题 I am working on a chat and using an array to hold the users. Here is my problem: User1 joins and is given Index 0 in the array via push. User2 joins and is given Index 1 in the array via push. User1 disconnects and is removed via splice. NOW User2 becomes Index 0. User1 reconnects and is given Index 1 via push. User2 disconnects, and Index 1 is removed which is now User1. This is of course causing a problem. So my question is how can I remove the item from the array without the index of the

问题 Yes, this question has been asked before. No, none of the answers I read could fix the problem I have. I'm trying to create a little Bounce game. I've created the bricks like this: def __init__(self,canvas): self.canvas = canvas self.brick1 = canvas.create_rectangle(0,0,50,20,fill=random_fill_colour(),outline=random_fill_colour()) self.brick2 = canvas.create_rectangle(50,0,100,20,fill=random_fill_colour(),outline=random_fill_colour()) self.brick3 = canvas.create_rectangle(100,0,150,20,fill

问题 Yes, this question has been asked before. No, none of the answers I read could fix the problem I have. I'm trying to create a little Bounce game. I've created the bricks like this: def __init__(self,canvas): self.canvas = canvas self.brick1 = canvas.create_rectangle(0,0,50,20,fill=random_fill_colour(),outline=random_fill_colour()) self.brick2 = canvas.create_rectangle(50,0,100,20,fill=random_fill_colour(),outline=random_fill_colour()) self.brick3 = canvas.create_rectangle(100,0,150,20,fill

问题 I believe when I create an identity column it gets indexed automatically, but I'm not 100% sure. Should I create an index for an identity column, or is it created automatically? 回答1: create table test (Id int identity) go sp_help test The object 'test' does not have any indexes, or you do not have permissions. No constraints are defined on object 'test', or you do not have permissions. As a general practice you would create a unique index on your identity column, this speeds up lookups.

问题 This question already has answers here : What is an IndexOutOfRangeException / ArgumentOutOfRangeException and how do I fix it? (4 answers) Closed 12 months ago . I'm aware of what the issue is stating but I am confused to how my program is outputting a value that's outside of the array.. I have an array of ints which is 0 - 8 which means it can hold 9 ints, correct? I have an int which is checked to make sure the users input value is 1-9. I remove one from the integer (like so) if (posStatus

问题 In Python, find and index are very similar methods, used to look up values in a sequence type. find is used for strings, while index is for lists and tuples. They both return the lowest index (the index furthest to the left) that the supplied argument is found. For example, both of the following would return 1 : "abc".find("b") [1,2,3].index(2) However, one thing I'm somewhat confused about is that, even though the two methods are very similar, and fill nearly the same role, just for

问题 I'm iterating through an array in ruby with each. Is there an easy way to get the iteration number or array index without going back to a for loop? 回答1: Ah, got it. each_with_index woo! edit: whoops! 回答2: For completeness' sake. Thing.each_with_index {|obj, index_num| puts [obj, index_num].join(" has an index of ")} 来源： https://stackoverflow.com/questions/706115/how-to-get-the-array-index-or-iteration-number-with-an-each-iterator

问题 I am writing a C# winform application for an archiving system. The system has a huge database where some tables would have more than 1.5 million records. What i need is an algorithm that indexes the content of these records. Mainly, the files are Microsoft office, PDF and TXT documents. anyone can help? whether with ideas, links, books or codes, I appreciate it :) example: if i search for the word "international" in a certain folder in the database, i get all the files that contain that word

问题 Given a list a containing vectors of unequal length and a vector b containing some elements from the vectors in a , I want to get a vector of equal length to b containing the index in a where the element in b matches (this is a bad explanation I know)... The following code does the job: a <- list(1:3, 4:5, 6:9) b <- c(2, 3, 5, 8) sapply(b, function(x, list) which(unlist(lapply(list, function(y, z) z %in% y, z=x))), list=a) [1] 1 1 2 3 Replacing the sapply with a for loop achieves the same of

问题 Is there a way to check if an array index exists or is null ? isset() doesn't tell you whether the index doesn't exist or exists but is null. If I do : isset($array[$index]) || is_null($array[$index]) it won't work because if the index doesn't exist is_null will crash. How can I check this please? Also is there a way to check only if something exist, no matter if it is set to null or not? 回答1: The function array_key_exists() can do that, and property_exists() for objects, plus what Vineet1982