add

问题 I am just trying to figure out how immutable things like a List are working, and how I can add things to it? I am very sorry for asking such dumb questions, but why is here my list always empty when printing it out? var end = false val list = List() while (!end) { val input = scala.io.StdIn.readLine("input:") if (input == "stop" ) end = true else input :: list } println(list) } Sorry for my inconvenience and this rather stupid question! 回答1: I am just trying to figure out how immutable things

问题 A little more sophisticated as my question mentioned below. I learned to use arrays more, but it screws things up too. Input: { "a": [ { "b": "c", "d": "e" }, { "b": "f", "d": "g" } ], "h": [ { "b": "c", "i": "j" }, { "b": "f", "i": "k" } ] } desired output: { "l": [ { "b": "c", "d": "e", "i": "j" }, { "b": "f", "d": "g", "i": "k" } ] } Things that I've tried, based up on JQ How to merge multiple objects into one { x: [ inputs | .a[] | { (.h[]): .i } ] | add} 回答1: The key to a simple solution

问题 I have a data frame with 2 variables. the first column "X" represents date and time with format dd/mm/yyyy hh:mm, the values in the second column "Y" are the electricity meter reading which are taken each after 5 minutes. Now I want to add the values of each half an hour. For instance X Y 13/12/2014 12:00 1 13/12/2014 12:05 2 13/12/2014 12:10 1 13/12/2014 12:15 2 13/12/2014 12:20 2 13/12/2014 12:25 1 At the end i want to present a result as: 13/12/2014 12:00 9 13/12/2014 12:30 12 and so on...

问题 I want to Read, Add and Delete users from a Windows using .NET code. How can I do that? 回答1: Here's some sample code for creating a windows user: public static bool CreateLocalWindowsAccount(string username, string password, string displayName, string description, bool canChangePwd, bool pwdExpires) { try { PrincipalContext context = new PrincipalContext(ContextType.Machine); UserPrincipal user = new UserPrincipal(context); user.SetPassword(password); user.DisplayName = displayName; user.Name

问题 I've a funny idiotic problem: Why is javascript showing that 10.2 - 17 = -6.800000000000001 ? Found something similar here: Calculate a minus operation in javascript returns a incorrect value but I can't round the numbers. Can I somehow fix this without specifying how many decimals to use? (I actually have some results that can have 6-7 decimals) 回答1: Floating point arithmetic is not always precise. In particular there is no exact representation of 10.2 as a floating point value, so the

问题 I want to add a size_t type to a pointer. Some like this: void function(size_t sizeA,size_t sizeB){ void *pointer; pointer=malloc(sizeA); pointer=pointer+sizeB; } In the hipothetic case that this will not end in a segfault, the question is: Can I do this? Add a type size_t to a pointer? And the resulting address will be in the address 'size'? 回答1: Can I do this [add size_t to a pointer]? Yes, you can, provided that you cast void pointer to some other type: pointer = ((char*)pointer) + sizeB;

问题 How to add 3 results with js ? I mean I have 3 calculators and I got a result from each one. How to combine them into one result ? Like if one is 3 and another is 7 it would get me : 10 l. But the 3 and the 7 are the result of other multiplications... For me I have to calculate the c + f + j. Here is my code : var a = document.getElementById("a"); var b = document.getElementById("b"); var c = document.getElementById("c"); var d = document.getElementById("d"); var e = document.getElementById(

问题 I have a table in MySQL InnoDB created like that: CREATE TABLE `users` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `type` enum('MANUAL','FACEBOOK') NOT NULL DEFAULT 'MANUAL', `role` enum('COOK','HOST','ALL') NOT NULL DEFAULT 'ALL', `about_me` varchar(1000) DEFAULT NULL, `food_preferences` varchar(1000) DEFAULT NULL, `cooking_experience` varchar(1000) DEFAULT NULL, `with_friend` bit(1) DEFAULT b'0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 Next I tried adding a

问题 I have this string 1010081-COP-8-27-20110616214459 I need to count the last 6 characters starting from the end of this string (because it could may be long starting from the begin) Then I need to add colons after every 2 characters. So after counting 6 characters from the end it will be 214459 After having added the colons it will look like: 21:44:59 Can you help me achieving it? I do not really know where to start! Thank you 回答1: You can do this with substr, str_split and implode The code is

问题 I tried to add the android platform by: $ cordova platform add android I get that out: Creating android project... /usr/local/lib/node_modules/cordova/node_modules/q/q.js:126 throw e; ^ Error: An error occured during creation of android sub-project. /Users/jannisportmann/.cordova/lib/android/cordova/3.3.0/bin/node_modules/q/q.js:126 throw e; ^ Error: The command "android" failed. Make sure you have the latest Android SDK installed, and the "android" command (inside the tools/ folder) is added