c++ - vector to int vs. vector to int -

c++ - vector<char> to int vs. vector<wchar_t> to int -

so had next function:

template < typename t > void someclass::readbinary(t& res) { size_t sbytestoread = sizeof(t); res = 0; std::vector<char> vcbuffer(sbytestoread); m_fstream.read(&vcbuffer[0], sbytestoread); // tbd - utilize reintepert_cast res = reinterpret_cast<t>(&vcbuffer[0]); }

where m_fstream std::fstream.

this function worked expected. when changed m_fstream type std::wfstream , adjust function little:

template < typename t > void someclass::readbinary(t& res) { size_t sbytestoread = sizeof(t); res = 0; std::vector<wchar_t> vcbuffer(sbytestoread); // type of vector changed m_fstream.read(&vcbuffer[0], sbytestoread); // tbd - utilize reintepert_cast res = reinterpret_cast<t>(&vcbuffer[0]); }

i different result (meaning different int value res). kinda expected have issue here. reading bytes file different in both cases.

i'm little lost , don't know how resolve this. idea?

note

t either: uint8_t, uint16_t & uint32_t

if want read binary value stream, need this:

template < typename t > void someclass::readbinary(t& res) { m_fstream.read(&res, sizeof(res)); }

there no need allocate vectors of , no need reinterpret cast anything.

this std::fstream only. not utilize std::wfstream binary input, utilize std::fstream. sizeof(t) might odd sizeof(wchar_t) might even, cannot read exact amount of bytes need wfstream. if absolutely must utilize std::wfstream , absolutely sure sizeof(t) divides sizeof(wchar_t) can seek like

m_fstream.read(&res, sizeof(res)/sizeof(decltype(m_fstream)::char_type));

but have never tried this.

c++ type-conversion fstream