qualifiers

问题 The following piece of code compiles and runs with gcc version 4.7.2 (Debian 4.7.2-5) : #include <stdio.h> int main() { const volatile x = 3; volatile const y = 4; return 0; } Should I assume that the order of const and volatile is irrelevant? I tried reading up here : encpp ref and it doesn't say anything about the order(or I'm missing it?) 回答1: Yes, the order is irrelevant. In C++, the relevant specification is in 7.1p1, decl-specifier and decl-specifier-seq , which basically explain that

问题 I wanna create a layout compatible with a very large number of devices and screens. As I have been researching I found out that the most common screen resolutions are 249x320, 480x800, 600x1024, 720x1280 (and some other screens proportional to these). Well, after reading the documentation I found out that there are two ways of doing it. Up to the 3.2 Android version I could use qualifiers for the layouts like "small, normal, large, xlarge" and combine them with "port" (portrait orientation)

来源： https://stackoverflow.com/questions/21189997/c-discards-qualifiers

问题 In this answer the OP used: static int const var = 5; in the context of a Conditional Compilation Control. Is there a difference between using static const int and static int const ? Like for example: static const int var; vs. static int const var; I don´t know the technique to imply the type in the middle between static and const . Is there a difference? 回答1: The grammar for declaration specifiers is given in C 2018 6.7 1, and it shows that specifiers for storage class (such as static ),

问题 I have two structs: // ----- non-const ----- struct arg_adapter { EArgType type; // fmtA, fmtB, ... union { TypeA * valueA; TypeB * valueB; // ... more types } arg_adapter(TypeA & value) : type(fmtA), valueA(&value) {} arg_adapter(TypeB & value) : type(fmtB), valueB(&value) {} // ... } // ----- const version ----- struct const_arg_adapter { EArgType type; // fmtA, fmtB, ... union { TypeA const * valueA; TypeB const * valueB; // ... more types } arg_adapter(TypeA const & value) : type(fmtA),

问题 I have two structs: // ----- non-const ----- struct arg_adapter { EArgType type; // fmtA, fmtB, ... union { TypeA * valueA; TypeB * valueB; // ... more types } arg_adapter(TypeA & value) : type(fmtA), valueA(&value) {} arg_adapter(TypeB & value) : type(fmtB), valueB(&value) {} // ... } // ----- const version ----- struct const_arg_adapter { EArgType type; // fmtA, fmtB, ... union { TypeA const * valueA; TypeB const * valueB; // ... more types } arg_adapter(TypeA const & value) : type(fmtA),

问题 I'd like to kind of pass-through a qualifier annotation using CDI. With that I mean that I'd want to add a qualifier to an injection point with that qualifier not being applied directly for the "first-level" injection target (because there is only one implementation for this) but a field within ("2nd level") the injected EJB. Is this possible with CDI? Does it maybe already work out-of-the-box? It should look similar to: @Stateless public class MyFirstLevelEJB { @Inject //this guy has

问题 The below simple VBS example retrieves CPU caption, architecture and family from WMI: s = "" For Each Item In GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\Root\CIMV2").InstancesOf("Win32_Processor") s = s & "Caption = " & Item.Caption & vbCrLf s = s & "Architecture = " & Item.Architecture & vbCrLf s = s & "Family = " & Item.Family & vbCrLf Next WScript.Echo s The output for me is: Caption = Intel64 Family 6 Model 42 Stepping 7 Architecture = 9 Family = 198 What I want is to

问题 In this document, under the section labeled "Variable Qualifiers", Apple says: You should decorate variables correctly. When using qualifiers in an object variable declaration, the correct format is: ClassName * qualifier variableName; for example: MyClass * __weak myWeakReference; MyClass * __unsafe_unretained myUnsafeReference; Other variants are technically incorrect but are “forgiven” by the compiler. To understand the issue, see http://cdecl.org/. Looking at cdecl.org doesn't clarify

问题 I am almost sure this has been asked before. Unfortunately, my C++ has become so rusty that I don't even know what to search for. Is there an easy-to-remember rule of thumb that would tell me which qualifiers ( inline , virtual , override , const , mutable , etc.) must appear (a) only in the declaration, (b) only in the definition, (c) both in the declaration and definition when I define a member function out-of-line? Example: struct Geometry { … virtual Geometry* clone() const = 0; }; struct