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Make a C++ initializer automatically detect union member?


Make a C++ initializer automatically detect union member?

By : user2953721
Date : November 21 2020, 01:01 AM
this will help OK, the standard still says that brace-initializing a union initializes only the first member. I suppose this puts this question more in the "Wouldn't it be nice if...?" category. , Update
In my introduction I mentioned:
code :
struct init {
    init(long    long   v) : t(type::longlong), x(v) {}
    init(char    const* v) : t(type::pcsz),     s(v) {}
    init(wchar_t const* v) : t(type::pwcsz),    w(v) {}

    enum class type { longlong, pcsz, pwcsz } t;
    union { long long x; char const* s; wchar_t const* w; };
};
init initial_data [] = {
    3 ,      // initializes x, brace elision
    "foo" ,  // initializes s 
    L"Foo"   // initializes w
};
#define BOOST_VARIANT_MINIMIZE_SIZE
#include <boost/variant.hpp>

using init = boost::variant<long long, char const*, wchar_t const*>;

#include <iostream>

int main() {
    init initial_data [] = {
        3 ,      // initializes x, brace elision
        "foo" ,  // initializes s 
        L"Foo"   // initializes w
    };

    for(auto& v : initial_data)
        std::cout << v.which() << "\t" << v << "\n";
}
0   3
1   foo
2   0x401f14


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How to make initializer list and class member initializer work together?

How to make initializer list and class member initializer work together?


By : samkhanaan
Date : March 29 2020, 07:55 AM
Any of those help By having the initialization of non-static data members at the point of declaration, your class is no longer an aggregate (see 8.5.1 Aggregates [decl.init.aggr]).
A workaround is to add a two-parameter constructor. This allows you to use initializer-list initialization, which allows same syntax as aggregate initialization, even if your class is not technically an aggregate.
code :
struct X {
  X(int x, int y) : x(x), y(y) {}
    int x = 1;
    int y = 1;
};

int main() 
{
    X x1{1, 2};
    X x2 = {1,2};
}
c2797 List initialization inside member initializer list or non static data member initializer not implemented

c2797 List initialization inside member initializer list or non static data member initializer not implemented


By : user3062807
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further Visual Studio did not implement this feature yet. An workaround can be found here
You can just use
code :
const ProcessingOrder m_ProcessingOrder = ProcessingOrder
{
  Process::TUNNEL_IP_VERSION,
  Process::PADDING_BYTE,
  Process::IP_ADDRESS_FIT_IPv6_SIZE,
  Process::PORT_NUMBER
};
struct Attribute_t{
         SSL_CTX* const m_pContext;
         Socket* m_pSocket;
         X509* m_pCertificate;
         }m_Attribute;
m_Attribute = Attribute_t{SSL_CTX_new(g_SSLChoice[version].m_pfSSLMethod()),
0, 0}
Initializer list doesn't detect publicly inherited member

Initializer list doesn't detect publicly inherited member


By : Gwendolyn Lee
Date : March 29 2020, 07:55 AM
may help you . You can't initialize x from the initializer list of class B, because only class A can initialize its members.
By the way, making the data members public is not a good idea. Here is an example of how your code would work:
code :
#include <iostream> 
using namespace std;

class A
{
public:
    A(int x, int y) : x(x), y(y) {}
protected:

    int x;
    int y;
};

class B : public A
{
public:

    B() : A(1, 5000)
    {
        y = 2;
    }
};

int main()
{   
    return 0;
}
What's the differences between member initializer list and default member initializer on non-static data member?

What's the differences between member initializer list and default member initializer on non-static data member?


By : user5245543
Date : March 29 2020, 07:55 AM
hope this fix your issue Member initialization
In both cases we are talking about member initialization. Keep in mind that the members are initialized in the sequence in which they are declared in the class.
code :
Test() : count(10) {
private:
    int count=10;
struct A {
int i = / some integer expression with side effects / ;
A(int arg) : i(arg) { }
// ...
};
Is it legal to initialize multiple overlapping fields in a union's member initializer list?

Is it legal to initialize multiple overlapping fields in a union's member initializer list?


By : Carlos José Díaz Bas
Date : March 29 2020, 07:55 AM
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