g++

问题 This compiles perfectly fine with the current MSVC compiler: struct Foo { } const foo; However, it fails to compile with the current g++ compiler: error: uninitialized const 'foo' [-fpermissive] note: 'const struct Foo' has no user-provided default constructor If I provide a default constructor myself, it works: struct Foo { Foo() {} } const foo; Is this another case of MSVC being too permissive, or is g++ too strict here? 回答1: The C++03 Standard: 8.5 [dcl.init] paragraph 9 If no initializer

问题 I would like to create a struct that has a certain alignment. I would like to use the same struct definition for both GCC and VisualC++ compilers. In VisualC++, one typically does this: __declspec(align(32)) struct MyStruct { // ... }; In GCC, one typically does this: struct MyStruct { // ... } __attribute__ ((aligned (32))); I could of course create the appropriate macros to make this work: BEGIN_ALIGNED_STRUCT(32) struct { // ... } END_ALIGNED_STRUCT(32) ; And thus be able to handle both

问题 I want to copy a string into a char array, and not overrun the buffer. So if I have a char array of size 5, then I want to copy a maximum of 5 bytes from a string into it. what's the code to do that? 回答1: First of all, strncpy is almost certainly not what you want. strncpy was designed for a fairly specific purpose. It's in the standard library almost exclusively because it already exists, not because it's generally useful. Probably the simplest way to do what you want is with something like:

问题 The following example will not compile using g++ 4.8.2: #include <iostream> #include <vector> using namespace std; int main() { vector<int> v {1, 2, 3}; v.erase(v.cbegin()); // Compiler complains return 0; } The compiler says the following. (It isn't very readable, but it's complaining that there's not a known conversion between vector<int>::const_iterator and vector<int>::iterator .) prog.cpp: In function ‘int main()’: prog.cpp:8:20: error: no matching function for call to ‘std::vector<int>:

问题 Is it possible to use a library compiled by visual studio in an application compiled by g++ (mingw) on Windows? 回答1: If the library is written in C++ and exposes a C++ interface: no (because the name-mangling differs between g++ and VC++). If the library is a static library written in C (or with an extern "C" interface): yes, but certain caveats apply. If the library is a DLL with a C interface: yes, but you'll have to create your own import library. 回答2: Also see the discussion for question

问题 Until some time ago, I thought a .a static library was just a collection of .o object files, just archiving them and not making them handled differently. But linking with a .o object and linking with a .a static library containing this .o object are apparently not the same . And I don't understand why... Let's consider the following source code files: // main.cpp #include <iostream> int main(int argc, char* argv[]) { std::cout << "main" << std::endl; } // object.hpp #include <iostream> struct

问题 I'm building some input checker that needs to have specific functions for integer and/or double (for example 'isPrime' should only be available for integers). If I'm using enable_if as a parameter it's working perfectly : template <class T> class check { public: template< class U = T> inline static U readVal(typename std::enable_if<std::is_same<U, int>::value >::type* = 0) { return BuffCheck.getInt(); } template< class U = T> inline static U readVal(typename std::enable_if<std::is_same<U,

问题 #ifndef __TEST__ #define __TEST__ namespace std { template<typename T> class list; } template<typename T> void Pop(std::list<T> * l) { while(!l->empty()) l->pop(); } #endif and used that function in my main. I get errors. Of course, I know that there are more template params for std::list (allocator I think). But, that is beside the point. Do I have to know the full template declaration of a template class to be able to forward declare it? EDIT: I wasn't using a pointer before - it was a

问题 I'm trying to understand how to compile C++ programs from the command line using g++ and (eventually) Clang on Ubuntu. I found a webpage which explains MakeFiles and I am following their directions. http://mrbook.org/tutorials/make/ I downloaded the four example files into their own directory. main.cpp hello.cpp factorial.cpp functions.h I then went ahead and ran their example of how to manually compile without a MakeFile. g++ main.cpp hello.cpp factorial.cpp -o hello When I ran the command

问题 I'm trying to understand how to compile C++ programs from the command line using g++ and (eventually) Clang on Ubuntu. I found a webpage which explains MakeFiles and I am following their directions. http://mrbook.org/tutorials/make/ I downloaded the four example files into their own directory. main.cpp hello.cpp factorial.cpp functions.h I then went ahead and ran their example of how to manually compile without a MakeFile. g++ main.cpp hello.cpp factorial.cpp -o hello When I ran the command