explicit

问题 I am doing some geocoding work that I used selenium to screen scrape the x-y coordinate I need for address of a location, I imported an xls file to panda dataframe and want to use explicit loop to update the rows which do not have the x-y coordinate, like below: for index, row in rche_df.iterrows(): if isinstance(row.wgs1984_latitude, float): row = row.copy() target = row.address_chi dict_temp = geocoding(target) row.wgs1984_latitude = dict_temp['lat'] row.wgs1984_longitude = dict_temp['long'

问题 // The Structure of the Container and the items public interface IContainer <TItem> where TItem : IItem { } public class AContainer : IContainer<ItemA> { } public interface IItem { } public class ItemA : IItem { } // Client app [Test] public void Test () { IContainer<IItem> container = new AContainer(); } Question : In test the following error occures. What can be the solution for casting? Cannot implicitly convert type 'AContainer' to 'IContainer'. An explicit conversion exists (are you

问题 This question already has answers here : Why isn't it possible to define implicit cast operator from interface to class? (2 answers) Closed 6 years ago . I'm just wondering if anyone knows the reason why you are not allowed to use interfaces with the implicit or explicit operators? E.g. this raises compile time error: public static explicit operator MyPlayer(IPlayer player) { ... } "user-defined conversions to or from an interface are not allowed" Thanks, 回答1: Section 10.9.3 of the C# spec

问题 Having recently introduced an overload of a method the application started to fail. Finally tracking it down, the new method is being called where I did not expect it to be. We had setValue( const std::wstring& name, const std::wstring& value ); std::wstring avalue( func() ); setValue( L"string", avalue ); std::wstring bvalue( func2() ? L"true", L"false" ); setValue( L"bool", bvalue ); setValue( L"empty", L"" ); It was changed so that when a bool value is stored we use the same strings

问题 When it comes to constructors, adding the keyword explicit prevents an enthusiastic compiler from creating an object when it was not the programmer’s first intention. Is such mechanism available for casting operators too? struct Foo { operator std::string() const; }; Here, for instance, I would like to be able to cast Foo into a std::string , but I don’t want such cast to happen implicitly. 回答1: Yes and No. It depends on which version of C++, you're using. C++98 and C++03 do not support

问题 I\'m trying to create the following structure: [StructLayout(LayoutKind.Explicit, Size=14)] public struct Message { [FieldOffset(0)] public ushort X; [FieldOffset(2)] [MarshalAs(UnmanagedType.ByValArray, SizeConst=5)] private ushort[] Y; [FieldOffset(12)] public ushort Z; } and I get the following error: Could not load type \'Message\' from assembly because it contains an object field at offset 4 that is incorrectly aligned or overlapped by a non-object field. Does anyone know why this is

问题 Is it possible to assign a base class object to a derived class reference with an explicit typecast in C#?. I have tried it and it creates a run-time error. 回答1: No. A reference to a derived class must actually refer to an instance of the derived class (or null). Otherwise how would you expect it to behave? For example: object o = new object(); string s = (string) o; int i = s.Length; // What can this sensibly do? If you want to be able to convert an instance of the base type to the derived

问题 What does the explicit keyword mean in C++? 回答1: The compiler is allowed to make one implicit conversion to resolve the parameters to a function. What this means is that the compiler can use constructors callable with a single parameter to convert from one type to another in order to get the right type for a parameter. Here's an example class with a constructor that can be used for implicit conversions: class Foo { public: // single parameter constructor, can be used as an implicit conversion