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问题 I've gone through loads of already asked questions but I haven't been able to find a solution for my problem. My application is a video finder, the user enters what he/she is looking for in a textbox and then selects from one of three websites(Youtube,Metacafe,Screen.yahoo) to find the video. Ive got a method for each of the choices but when it reaches the GetElementByID method it returns a null value for all three. Im going to assume ive missed something and thats why im having this null

问题 In PHP: $var = NULL; What happened here? Was NULL assigned to $var, or was $var created with unknown value because assigning NULL does nothing? Consider a for-loop $arr=array(); for($i=0;$arr[$i]=NULL;$i++){} that does break on this condition. This must mean that assigning of NULL is evaluated to FALSE, which means that assignment never took place and the value of $arr[0] is undetermined. A var_dump would simply give array(1) { [0]=> NULL } but I have never been sure what to make of that.

问题 I have the following check for nil: client = !deal['deal']['party']['party'].nil? ? deal['deal']['party']['party']['company_id'] : "" but still I get: You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.[] How can I prevent this? 回答1: I don't know Ruby, but I think it goes wrong before the .nil: deal['deal']['party']['party'] ^ ^ ^ The arrows indicate possible nil indexes. For example, what if [

问题 I need to do a query to get the result of an specific exam for each student , and I also want to display NULL for student who didn't enter his scores.... Here is my four table Student table Scores table Student student_subject My table link Score table (user_id) with Student table (user_id) Exam table ( id ) with scores table ( exam.id) student_subject ( user_id ) with student table ( user_id) student_subject (group_id) with exam table (group_id) (my group database is on another database for

问题 I have a large, messy report to write that joins across 5 tables. There is one column in one table that is being used for several different values--essentially a "tag" column, where the tags are used in creative ways depending on what kind of miscellaneous metadata the users want to use. As a result, my query for the report returns 3 nearly-identical rows that differ only in the "tag" column; for instance, I might get: NAME TAG EMAIL BOB A BOB@EXAMPLE.COM BOB B BOB@EXAMPLE.COM BOB C BOB

问题 I have a struct: type User struct { ID int `json:"id"` Username string `json:"username"` About string `json:"about"` IsAdmin bool `json:"is_admin"` Status int `json:"status"` ...... } A:= User{1,"admin", "I am a admin",status: 1,....} B:= User{ID:1, Username: "UserBBBB"} ...enter code here... B is {1, "UserBBBB", "I am a admin", 1, ...(same value in A)} object B has a few properties with nil (string), false (bool), 0 (int),... I want to check if a field of B is unassigned value, that field

问题 How can I remove the null values in the bottomcount, ie. i only want to see the products with actually sold units, I have tried with nonempty and non empty without success. with member [Measures].[Amount Sold] as ([Measures].[Internet Sales Amount]), format_string = "currency" select {[Measures].[Amount Sold]} on columns, bottomcount( order( {[Product].[Product].Members}, ([Measures].[Amount Sold]), bdesc), 5 )on rows 回答1: You could filter [Product].Members using NOT ISEMPTY() to exclude all

问题 I am going to access linkedin profile in my android app. I used the below code which is working fine on android devices, but getting crashed on emulator. Does't know where is the problem. My code is below. Config.java public class Config { public static String LINKEDIN_CONSUMER_KEY = "75rbbjsc94argh"; public static String LINKEDIN_CONSUMER_SECRET = "G85WTKgcIijk4U6Yu"; public static String scopeParams = "rw_nus+r_basicprofile+r_fullprofile+r_emailaddress+r_network+r_contactinfo+rw_groups+rw

问题 This question already has answers here : Can constructor return a null object? (9 answers) Closed 3 years ago . Is it possible for the following line to return null? MyClass obj = new MyClass(); If so, what conditions would cause a return value of null? 回答1: It's impossible for new to return null, assuming the VM is functioning correctly. From section 15.9.4 of the Java Language Specification: The value of a class instance creation expression is a reference to the newly created object of the

问题 I've been struggling with this for a while. I created a utility that allows you to open .TXT files. These text files contain PCL (Print Command Language). When I import a new file, it is being truncated by a \0 (NULL Terminator character). Because PCL files contain graphic images randomly throughout everything I import is truncated at the first bitmap image because the bitmap images start with NULL. This is the exact issue as seen here: Displaying Raw Data From Image File Using TextBox or