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问题 Within a webpage, upon loading, I fill a dataset with two table with a relation between those tables and then load the data into a repeater with a nested repeater. This can also occur after the user clicks on a button. The data gets loaded from a SQL database and the repeater datasource is set to the dataset after a postback. However, when ItemDataBound occurs the Item.Dataitem is always null. Why would this occur? Here is the databind code: this.rptCustomSpaList.DataSource = ds; this

问题 I got tired of waiting for compiler support of nullptr (gcc 4.6 does but it's so new few distributions support it). So as a stop gap until nullptr is fully supported I decided to emulate it. There are two examples of emulation: one from here, and one from wikibooks. Of note, neither implementation mentions an operator == . However, without one, the following code will not compile. int* ptr = nullptr; assert( ptr == nullptr ); // error here: missing operator == Is this operator == error a

问题 I am very new to javascript as I am currently making a cross platform web app in jQuery Mobile, I have used the example of XML Parsing to a HighCharts graph yet when I encounter a null in my series data it fails to draw any of the line and makes it into a scatter plot almost. // push data points $(series).find('data point').each(function(i, point) { seriesOptions.data.push( parseFloat($(point).text()) ); }); I have no idea how to write a if statement that checks to see if it found a null and

问题 I'm trying to replicate this in Java. To save you the click, it says that a character array ['F', 'R', 'A', 'N', 'K', NULL, 'k', 'e', 'f', 'w'] , when converted to a null-terminated string, will stop after 'K' , since it encounters a null pointer there. However, my Java attempts don't seem to be working. public class TerminatingStrings{ public static void main(String[] args){ char[] broken = new char[3]; broken[0] = 'a'; broken[1] = '\u0000'; broken[2] = 'c'; String s = new String(broken);

问题 How do I get my mysql database to return 0 if the neighborhood in the WHERE clause doesn't exist? So in the example below, Old Town is not in the database. I'd like the database to return 0 incidents instead of an empty result. SELECT incidents, neighborhoods FROM `myTable` WHERE neighborhoods ='Old Town' I also tried SELECT IFNULL(incidents,0), IFNULL(neighborhoods,0) FROM `myTable` WHERE neighborhoods ='Old Town' Any suggestions would be really appreciated. 回答1: My take on your issue is to

问题 I have already looked at existing topics, so please try to refrain from dropping links here. I want to get the value of a registry key - plain and simple. Here is what I have so far. Registry: 1) Made a key under Current_User\Software\Custom_Subkey\Custom_Value\Custom_key\string_value I am trying to find the string_value string reg_subKey = "Software\\Custom_Subkey\\Custom_Value"; RegistryKey root = Registry.CurrentUser.CreateSubKey(reg_subKey); foreach (string keyname in root.GetValueNames()

问题 My application is asp.net with vb. In my page I have a textbox for passing date. If I didn't enter date and on clicking submit, I have to pass null value to the stored procedure. I tried following codes such as DBNull.Value and DateTime.MinValue . In that case instead of null, "#12:00:00#" is passing. I have to pass Null. 回答1: Just assign the parameter the value DBNull.Value [EDIT] If you are using SqlParameter (thanks Jon) then you can set it like this if it gives any error parameter.Value =

问题 I'm accustomed to using __attribute__((nonnull)) when expressing pointers that should not be null. void f(int* ptr __attribute__((nonnull))); int main(){ int* ptr = new int(1); f(ptr); } void f(int* ptr){/*impl*/} However, with the GSL, there is also the not_null<T*> wrapper type. void function1(gsl::not_null n); void f(gsl::not_null<int*> n); int main(){ int* ptr = new int(1); f(ptr); } void f(gsl::not_null<int*> n){/*impl*/} Assuming the language facilities are there to support the GSL

问题 I made a Class that has several NSStrings as properties. If I have an object of this class, then how can I know if the object is nil (i.e. all the NSString properties are nil). My class looks like this // MyClass.h #import <Foundation/Foundation.h> @interface MyClass : NSObject <NSCoding> { NSString *string1; NSString *string2; } @property (nonatomic, retain) NSString *string1; @property (nonatomic, retain) NSString *string2; @end I'm checking it like this and it doesn't work if

问题 For example, I have an object x that might be None or a string representation of a float. I want to do the following: do_stuff_with(float(x) if x else None) Except without having to type x twice, as with Ruby's andand library: require 'andand' do_stuff_with(x.andand.to_f) 回答1: We don't have one of those but it isn't hard to roll your own: def andand(x, func): return func(x) if x else None >>> x = '10.25' >>> andand(x, float) 10.25 >>> x = None >>> andand(x, float) is None True 回答2: Taking off