hashtable

问题 Hi guys I have this warning on my code. I try to compile using @SuppressWarnings("unchecked") It compile but at the time of the execution the program can't find the main class. How can I solve this problem? Below the code: import java.util.*; @SuppressWarnings("unchecked") class ProgRub { public static void main(String argv[]) { Hashtable rubrica = new Hashtable(20); String chiave, valore; Menu mioMenu = new Menu(); int scelta; scelta = (int) mioMenu.scelta(); while (scelta != 5) { if (scelta

问题 I have some random test parameters for which I need to calculate a hash to detect if I ran with same parameters. I might run the test using the same source recompiled at a different time or run on a different machine. Even so I want to detect whether the same parameters were used for the run. Does std::hash give the same result for the same input for different compiled builds and different machines? e.g. std::hash<string>{}("TestcaseParamVal0.7Param0.4"); Will this always be a unique number?

问题 I know the difference between Hashtable and HashMap. However, both these classes seemingly are using a hash function to get the job done. Is there a difference between the hash function used in Hashtable, and the hash function used in HashMap? In particular, is there a difference between the hashing algorithm they use? What is the formula used to hash in these two classes? In other words, is the way for calculating index (hash value) different? 回答1: In particular, is there a difference

问题 I know the difference between Hashtable and HashMap. However, both these classes seemingly are using a hash function to get the job done. Is there a difference between the hash function used in Hashtable, and the hash function used in HashMap? In particular, is there a difference between the hashing algorithm they use? What is the formula used to hash in these two classes? In other words, is the way for calculating index (hash value) different? 回答1: In particular, is there a difference

问题 from another application I have key-value pairs which I want to use in my script. But there they have e.g. the keys "a" and "A" - which causes an Error double keys aren't allowed. $x = @{ "a" = "Entry for a"; "A" = "S.th.else for A" } What can I do as I would need both or none? Thanks in advance, Gooly 回答1: By default PowerShell Hash tables are not case sensitive. Try this $h = new-object System.Collections.Hashtable $h['a'] = "Entry for a" $h['A'] = "S.th.else for A" $h[0] = "Entry for 0" $h

问题 I'm trying to understand and use the kernel hash tables and I've already read this and this link, but I didn't understand none of them. My first question is: Why our struct has to have the struct h_list inside it? If we're gonna access our struct through the struct h_list our struct shouldn't be within struct h_list and not the opposite? After reading the tutorial I've tried to write the following code: DECLARE_HASHTABLE(nodes_hash, 3) hash_init(nodes_hash); struct h_node{ int data; char name

问题 I have a powershell Array object that is programmatically generated, something with arrays inside arrays, inside arrays, sometimes called a "property bag" or a "hashtable", but I think it's natively called an "Array containing Arrays" in the most native powershell terminology. For example: @{ Version = '1.0.0' Name = 'thing' Revision = 'c3a89cd20e19bb82f41e95e0806edc5b6cfd224e' Date = '2016-12-09' Build = '1234' Contents = @{ "index.html" = "23dd7b993f40bb3ae8848fe104b3b767" } } Generating a

问题 I have a powershell Array object that is programmatically generated, something with arrays inside arrays, inside arrays, sometimes called a "property bag" or a "hashtable", but I think it's natively called an "Array containing Arrays" in the most native powershell terminology. For example: @{ Version = '1.0.0' Name = 'thing' Revision = 'c3a89cd20e19bb82f41e95e0806edc5b6cfd224e' Date = '2016-12-09' Build = '1234' Contents = @{ "index.html" = "23dd7b993f40bb3ae8848fe104b3b767" } } Generating a

问题 What are the cases when using hash table can improve performance, and when it does not? and what are the cases when using hash tables are not applicable? 回答1: What are the cases when using hash table can improve performance, and when it does not? If you have reason to care, implement using hash tables and whatever else you're considering, put your actual data through, and measure which performs better. That said, if the hash tables has the operations you need (i.e. you're not expecting to

问题 The built in maps and sets in C++ libraries (including unordered_map and multimap) requires that the find function (used to lookup a specific element) utilize an iterator for traversing the elements. The C++ reference site claims that looking up elements using these data structures takes on average constant time, much like a regular hash table. But wouldn't an iterator have to traverse the entire list, making this O(n) time on average, before finding the element? 回答1: You statement are no