fork download

copy

#include <cstdlib>
#include <cassert>
 
#pragma pack (1)
 
template <size_t Width>
class Base
{
public:
    char mData [Width];
    template <typename Field> Field ExtractAs () const
    {
        return *reinterpret_cast <Field> (mData);
    }
};
 
template <typename FieldVal>
class IntegralField
:
    public Base <sizeof (FieldVal)>
{
public:
    FieldVal GetVal () const
    {
        return ExtractAs <FieldVal> ();
    }
};
 
int main()
{
    char raw[4] = {0x11, 0x22, 0x33, 0x44};
    typedef IntegralField <uint32_t> UInt32Field;
    const UInt32Field& field =
        *reinterpret_cast <const UInt32Field*> (raw);
    const uint32_t extracted = field.GetVal();
    assert (extracted == 0x11223344);
}
 

prog.cpp: In member function ‘FieldVal IntegralField<FieldVal>::GetVal() const’:
prog.cpp:25:16: error: ‘ExtractAs’ was not declared in this scope
prog.cpp:25:35: error: expected primary-expression before ‘>’ token
prog.cpp:25:38: error: expected primary-expression before ‘)’ token
prog.cpp: In function ‘int main()’:
prog.cpp:32:28: error: ‘uint32_t’ was not declared in this scope
prog.cpp:32:36: error: template argument 1 is invalid
prog.cpp:32:49: error: invalid type in declaration before ‘;’ token
prog.cpp:34:52: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
prog.cpp:35:11: error: ‘uint32_t’ does not name a type
prog.cpp:36:5: error: ‘extracted’ was not declared in this scope
prog.cpp:33:24: warning: unused variable ‘field’ [-Wunused-variable]

Standard output is empty