Re: Trying to come to terms with typecasting operators

From:
Rune Allnor <allnor@tele.ntnu.no>
Newsgroups:
comp.lang.c++.moderated
Date:
Mon, 23 Nov 2009 23:51:40 CST
Message-ID:
<6422baa6-ad97-43e8-83a2-3fb8f640d11e@m20g2000vbp.googlegroups.com>
Hm.

Wrote the code and the post in parallel, so I lost the
point first time around.

In the code below is the test using reinterpret_cast<>
added, along with the corresponding added output.
As can be seen, each char value is preceeded by a number
of leading zeros that I am unable to get rid of. I assume
this has something to do with memory footprints and/or byte
ordering (I am using VS2008 on a PC, which, according to

http://en.wikipedia.org/wiki/Endianness

means that the internal byte organization is little-endian).

Rune

--------------- Output ----------------
a) Naive output:
0 1 2 3

b) C-style type cast:
30 31 32 33

c) Type cast by variable assignment:
30 31 32 33


d) reinterpret_cast:
00000030 00000031 00000032 00000033

---------------------------------------

///////////////////////////////////////////////////////////////////////////?//
#include <iomanip>
#include <iostream>

int main()
{
        // Hex values of digits: 0 1 2 3
        unsigned char c[] = {0x30,0x31,0x32,0x33};
        std::cout << "a) Naive output:" << std::endl;
        for (size_t n = 0; n != 4; ++n)
        {
                std::cout << std::hex << c[n] << " ";
        }
        std::cout << std::endl << std::endl;

        std::cout << "b) C-style type cast:" << std::endl;
        for (size_t n = 0; n != 4; ++n)
        {
                std::cout << std::hex << (unsigned int) c[n] << " ";
        }
        std::cout << std::endl << std::endl;

        std::cout << "c) Type cast by variable assignment:" << std::endl;
        for (size_t n = 0; n != 4; ++n)
        {
                size_t d = c[n];
                std::cout << std::hex << d << " ";
        }
        std::cout << std::endl;


///////////////////////////////////////////////////
    std::cout << "d) reinterpret_cast:"
              << std::endl;
    for (size_t n = 0; n != 4; ++n)
    {
        std::cout << std::hex << reinterpret_cast<int*> (c[n]) << " ";
    }
    std::cout << std::endl << std::endl;
///////////////////////////////////////////////////

        return 0;

}


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