Re: casting X* to char*

Tom1s posted:


Here's a little program I threw together for giving the different pointer
sizes on a given platform. On Windows XP, it gives 4 for every one.

#include <iostream>
#include <cstdlib>
#include <cstring>

/* The following are only use for their types */
#include <string>
#include <vector>
#include <typeinfo>

template<unsigned width>
const char* CentreHoriz( const char* const p_in )
{
    /* NB:

       (1) Uses static data, so be careful with sequence points.
       (2) Doesn't check that string isn't too long.
    */

    static char buffer[width + 1]; /* Automatic null terminator */

    std::memset( buffer, ' ', width * sizeof(*buffer) );

    unsigned const len = std::strlen(p_in);

    std::memcpy( buffer + width / 2 - len / 2,
                 p_in,
                 len);

    return buffer;
}

template<class T>
void PrintRow( const char* const p )
{
   std::cout
         << '|'
         << CentreHoriz<36>(p)
         << "|| "
         << sizeof(T)
         << " |\n"

    <<
    "-------------------------------------------------------------\n";
}

int main()
{
    std::cout <<
    "=============================================================\n"
    "| How much memory does a particular pointer type consume? |\n"
    "=============================================================\n"
    "| Type || Bytes |\n"
    "=============================================================\n";

    PrintRow<char*>("char*");
    PrintRow<short*>("short*");
    PrintRow<int*>("int*");
    PrintRow<long*>("long*");
    PrintRow<float*>("float*");
    PrintRow<double*>("double*");
    PrintRow<long double*>("long double*");
    PrintRow<bool*>("bool*");
    PrintRow<wchar_t*>("wchar_t*");
    PrintRow<std::string*>("std::string*");
    PrintRow<std::vector<std::string>*>("std::vector<std::string>*");

    std::cout << '\n';

    std::system("PAUSE");
}

-Tom1s