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问题 If I do the following: List<GenericClass> listObj = new List<GenericClass>(100); // Do I need this part too? for (int i = 0; i < 100; i++) { listObj[i] = new GenericClass(); } Basically I am asking if the C# compiler will automatically fire the GenericClass constructor for each of the 100 GenericClass objects in the list. I searched in the MSDN documentation as well as here on StackOverflow. Thanks for any help. 回答1: That's not how List works. When you specify a capacity, it's an initial

问题 If I do the following: List<GenericClass> listObj = new List<GenericClass>(100); // Do I need this part too? for (int i = 0; i < 100; i++) { listObj[i] = new GenericClass(); } Basically I am asking if the C# compiler will automatically fire the GenericClass constructor for each of the 100 GenericClass objects in the list. I searched in the MSDN documentation as well as here on StackOverflow. Thanks for any help. 回答1: That's not how List works. When you specify a capacity, it's an initial

问题 I'm trying to add a constraint to a table so that it displays one of the columns as the current date plus 10 days. Here's what I've tried so far (I'm very new to SQL): ALTER TABLE orders ADD CONSTRAINT default_date DEFAULT DATEADD (DAY,10,required_date) FOR required_date Halp! Edit: I've also tried this now: ALTER TABLE orders ALTER COLUMN required_date ADD CONSTRAINT required_date_plus_ten DEFAULT DATEADD (DAY,10,required_date) Edit: Thanks to ypercube & my classmate. The final code is:

问题 I have a base class called Handle from which I derive several base classes such as RectHandle and EllipseHandle . In those subclasses I have attempted to override the default style key to point to Handle but a style targeting Handle is not applied. I still have to explicitly target RectHandle or EllipseHandle either directly, or via a 'BasedOn' style. What am I missing? Here's the MSDN excerpt for DefaultStyleKeyProperty: A control typically overrides the default value of this property to be

问题 I have built a small ruby webservice, in this I have implemented cancan authorization. I followed this tutorial. The problem is that, I can't find out the way to assign at the user, when they do the registration to my site, the base role level. I find out to do this with a checkbox, but it's not what I want. My idea was to put this assignment directly into the registrations_controller, but I failed to save the role. I hope that somebody can help me. Thank you. 回答1: This is what worked for me

问题 Why won't this work? In generic.xaml for a custom control: In the style applied to the custom control... <Setter Property="ChromeContent"> <Setter.Value> <Grid /> </Setter.Value> </Setter> ... Later, in the control template... <ContentPresenter Grid.Column="0" x:Name="ChromeContentPresenter" Content="{TemplateBinding ChromeContent}" /> Here's the dependency property for ChromeContent... public Object ChromeContent { get { return (Object)GetValue(ChromeContentProperty); } set { SetValue

问题 So, I've been looking at boost::array but it does require default constructor defined. I think the best way of filling this array with data, would be through a push_back(const T&) method. Calling it more times than SIZE (known at compile-time) would result in assert or exception, depending on build configuration. This way it would always contain meaningful data. Does anyone know efficient, portable, reliable implementation of this concept? 回答1: Well, I would have thought that someone would

问题 As I retrieve data from a database table an array is populated. Some of the fields are defined as decimal & money fields and within the array they are represented as BigDecimal. I use these array values to populate a CSV file, but the problem is that all BigDecimal values are by default represented in Scientific format (which is the default behaviour of the BigDecimal to_s method). I can show the values by using to_s('F'), but how can I override the default? 回答1: This is built on @Farrel's

问题 As I retrieve data from a database table an array is populated. Some of the fields are defined as decimal & money fields and within the array they are represented as BigDecimal. I use these array values to populate a CSV file, but the problem is that all BigDecimal values are by default represented in Scientific format (which is the default behaviour of the BigDecimal to_s method). I can show the values by using to_s('F'), but how can I override the default? 回答1: This is built on @Farrel's

问题 What's the idiom in Ruby when you want to have a default argument to a function, but one that is dependent on another parameter / another variable? For example, in Python, an example is: def insort_right(a, x, lo=0, hi=None): if hi is None: hi = len(a) while lo < hi: mid = (lo+hi)//2 if x < a[mid]: hi = mid else: lo = mid+1 a.insert(lo, x) Here, if hi is not supplied, it should be len(a) . You can't do len(a) in the default argument list, so you assign it a sentinel value, None, and check for