sizeof (long double)

From:

K4 Monk <k4monk@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 18 Feb 2011 08:00:09 -0800 (PST)

Message-ID:

<d9bf17c3-5317-4dc9-8185-7466bc22e457@y4g2000prh.googlegroups.com>

#include<iostream>
using namespace std;
int main()
{
    cout<<sizeof(double)<<" "<<sizeof(long double)<<endl;
    return 0;
}

this on my computer prints:
8 16

However, with a different program I wrote to check out all different
types, sizeof(long double) print 10, Why? below is the code

#include<iostream>
#include <climits>
#include <cstdio>
#include <cstring>
#include <typeinfo>
#include <string>
using namespace std;

template <typename T>
void print_representation(T*addr){
  unsigned char* chaddr = (unsigned char*)addr;
  for(size_t q=0;q<sizeof(T); ++q){
    for (int bit=CHAR_BIT;bit > 0 ;--bit){
      std::cout << ((*(chaddr+q)&(1U<<(bit-1))) ? 1 : 0);
    }
  }
  std::cout<<std::endl;

}

template <typename T>
void print(T* addr, const string& s="")
{
    unsigned char* chaddr=reinterpret_cast<unsigned char*> (addr);
    cout<<"address of pointer "<<std::hex<<addr;
    cout<<" sizeof object: "<<sizeof(*addr);
    cout<<" type of object: "<<typeid(*addr).name()<<" "<<s<<endl;

}

int main()
{
    //char types
    bool b=1;
    print<bool> (&b);

    char c='A';
    print<char> (&c);

    short s=1;
    print<short> (&s);

    short int si=2;
    print<short int> (&si);

    int i=10;
    print<int> (&i);

    long l=5;
    print<long> (&l);

    long int li=6;
    print<long int> (&li);

    /*
    enum color { blue, red, white };
    color c1 = blue;
    print<enum> (&c1);
    */

    // unsigned types

    unsigned char c1='B';
    print<unsigned char> (&c1);

    unsigned short us=10;
    print<unsigned short> (&us);

    unsigned short int usi=11;
    print<unsigned short int> (&usi);

    unsigned int ui=11;
    print<unsigned int> (&ui);

    unsigned long ul=12;
    print<unsigned long> (&ul);

    unsigned long int uli=14;
    print<unsigned long int> (&uli);

    //floating point types
    float f=3.1415;
    print<float> (&f);

    double d=2.71828;
    print<double> (&d);

    long double ld=1.414214;
    print<long double> (&ld);

    cout<<sizeof(long double)<<endl;

   return 0;
}