null

iOS: NSString loses URL, (null) is shown

由 白昼怎懂夜的黑 提交于 2019-12-14 02:29:21
问题 This is my Code so far: NSString *listedImageURL = listedProduct.image; NSLog(@"URL: %@", listedImageURL); This Code works fine and NSLog shows me the correct URL. But when I try the following Code, NSLog shows up (null): NSString *listedImageURL = listedProduct.image; NSURL *imageURL = [NSURL URLWithString:listedImageURL]; NSData *imageData = [NSData dataWithContentsOfURL:imageURL]; UIImage *image = [UIImage imageWithData:imageData]; What am I doing wrong?? 回答1: I believe that relower is on

Why does TSQL operator + behave differently than aggregation function sum()

由 房东的猫 提交于 2019-12-14 02:14:32
问题 There is a strange behaviour of TSQL: SELECT 1 + NULL returns NULL , while SELECT sum(someColumn) will always return an integer, ignoring null values, unless the whole column is null (in which case it returns null). What are the design choices behind the decision to make binary operators different in meaning from matching aggregate functions? Is there a way to overcome this 'limitation', except litteraly stuffing my SQL with coalesce()? (edited after comments) 回答1: This behaviour is common to

.NET DBNull vs Nothing across all variable types?

由 戏子无情 提交于 2019-12-14 00:51:41
问题 I am a little confused about null values and variables in .NET. (VB preferred) Is there any way to check the "nullness" of ANY given variable regardless of whether it was an object or a value type? Or does my null check have to always anticipate whether it's checking a value type (e.g. System.Integer) or an object? I guess what I'm looking for is a function that checks all possible kind of null-ness. That is, any type of variables that a) were never assigned a value since declared b) were

Check if null before set to null?

由 走远了吗. 提交于 2019-12-13 23:16:55
问题 Should we check if variable is null before setting it to null? if (MyBills != null) { MyBills = null; } For, example, in a Java related question the performance implications are minimal. Is this the case in C#? Other implications? Testing I've created the following code to test: var watch = System.Diagnostics.Stopwatch.StartNew(); int iterations = int.MaxValue; List<int> myBills= null; for (var i = 0; i < iterations; i++) { if (myBills!= null) { myBills = null; } } watch.Stop(); var elapsedMs

My script works in jsfiddle but not site. Cannot call method hover of null?

由 一曲冷凌霜 提交于 2019-12-13 22:51:34
问题 I'm getting an error that says "Uncaught typeError: cannot call method 'hover' of null" after $('#nav li a').hover(function(){ in my javascript. site code: http://pastebin.com/GjZBEu3s jsfiddle: http://jsfiddle.net/jenga/5rfCC/2/ 回答1: You scripting should be in the body of the document, right before the closing </body> tag. If it's loaded in the <head> , the elements it addresses in the document may not be loaded yet. See this jsfiddle (notice 'no wrap (body)' in the 'Choose framework' dialog

Confusing null compares combined with NOT

由 前提是你 提交于 2019-12-13 22:07:31
问题 I realize that comparing NULL to any other value (including NULL ) will always result in false. DECLARE @IsSet bit = NULL; SELECT IIF(@IsSet = 1, 'true', 'false') SELECT IIF(@IsSet != 1, 'true', 'false') This outputs: false false But this is part that confuses me: SELECT IIF(NOT(@IsSet = 1), 'true', 'false') SELECT IIF(NOT(@IsSet != 1), 'true', 'false') This also outputs: false false I would expect that the NOT would have flipped the value to TRUE. (Which it does if @IsSet is set to 0 for the

Absolute Positioning a JButton

由 為{幸葍}努か 提交于 2019-12-13 21:54:49
问题 I am trying to position a JButton with a null layout but it will not show up, if i switch to gridlayout they are only lined up in the middle no matter what i change. How can i set the position and size of my button? In Frame package Run; import javax.swing.*; import ThreeD.Display; import ThreeD.Launcher; import TowerDefence.Window; import java.awt.*; import java.awt.image.BufferedImage; public class Frame extends JFrame{ public static String title = "Game"; /*public static int

NHibernate one-to-many foreign key is NULL

由 烈酒焚心 提交于 2019-12-13 20:22:24
问题 I have a problem with NHibernate. What i am trying to to is very simple: I have two Classes. UserTicket and UserData. A UsertTicket has some UserData and a UserData belongs to one UserTicket: public class UserData{ public virtual int Id { get; set; } public virtual String PDF_Path { get; set; } } public class UserTicket { public virtual int Ticketnr { get; set; } public virtual IList<UserData> UserData { get; set; } } And here the mappig xml: <class name="UserTicket" table="UserTicket"> <id

Return value of variables that is not null

由 懵懂的女人 提交于 2019-12-13 20:16:37
问题 what is the best way in python to return the value of 3 variables, that is not null. only 1 of the variable will not be null at any time. so far i am using this non efficient code if kwargs.get('F06_yes_1'): context1.update({'F06_1': kwargs['F06_yes_1']}) elif kwargs.get('F06_no_1'): context1.update({'F06_1': kwargs['F06_no_1']}) else: context1.update({'F06_1': kwargs['F06_na_1']}) Furthermore, to do the replacement (based on your comments), you can try: context1.update({ 'F06_1': ('yes' if

Looking NULL values for different Oracle Type

由 假装没事ソ 提交于 2019-12-13 20:09:19
问题 I'm doing collection of two columns(col & val). Into second select col is parameter of other columns and val is value of this column. declare TYPE t_my_list is record(id varchar2(1000), col VARCHAR2(4000),val VARCHAR2(4000)); TYPE list_3STR is table of t_my_list; v_stmt VARCHAR2(32000) := 'SELECT id, col, val FROM userA.tableA'; v_lstmt VARCHAR2(32000); v_ret list_3STR := list_3STR(); cDel number; begin EXECUTE IMMEDIATE v_stmt BULK COLLECT INTO v_ret; for i in v_ret.first..v_ret.last loop v
订阅 null