#include <stdio.h>
#include <stdlib.h>

int main()
{
    int i;
//    double x = 0.15 / 3. * (2.1 + 7.9), y = 1.0 / 3.0 * 1.5;
//    double x = 0.15 / 3. * 10.0, y = 1.0 / 3.0 * 1.5;
    double x = 0.4 * 1.2 / 1.1, y = 0.4 / 1.1 * 1.2;
    unsigned char *ptr;
    if (x - y)
        printf("not equal\n");
    printf("%f (%.17f)\n", x, x);
    printf("%f (%.17f)\n", y, y);

    printf("This is IEEE 754 64bit double\n");
    printf("Use online calculator to evaluate\n");
    printf("  http://babbage.cs.qc.cuny.edu/IEEE-754.old/64bit.html\n");

    ptr = (unsigned char *) &x;
    for (i=7; i>=0; i--)
        printf("%02x", ptr[i]);
    printf("\n");

    ptr = (unsigned char *) &y;
    for (i=7; i>=0; i--)
        printf("%02x", ptr[i]);
    printf("\n");

    system("pause");
    return 0;
}

/*

VC2010, 32bit XP, cl floatingComparison.cpp
GCC 4.8.1, 32bit XP, g++ floatingComporison.cpp -o floatingComparison.exe
not equal
0.500000 (0.49999999999999994)
0.500000 (0.50000000000000000)
This is IEEE 754 64bit double
Use online calculator to evaluate
  http://babbage.cs.qc.cuny.edu/IEEE-754.old/64bit.html
3fdfffffffffffff
3fe0000000000000

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

*/