/*
	Fooling around with floating point numbers.
	This code uses some tricks with addresses
	and type-casting to help you see the
	internal structure of float variables.

	This code assumes that your C compiler
	treats float variables as IEEE 754
	32-bit floating point numbers, and that
	unsigned int variables are 32-bit variables.

	At a terminal with the gcc compiler
	installed, you can compile this program
	like so:

       gcc -o floatingpoint floatingpoint.c

	and then just run it with:

	   ./floatingpoint
	
	Have fun!

	Jeff Ondich
	Last updated 14 Oct 2016
 */
#include <stdio.h>

int main() {
    float x, y, z;

    x = -6.375;
    float *addressOfX = &x;
    unsigned int *addressOfXInterpretedAsInteger = (unsigned int *)addressOfX;
    unsigned int xInterpretedAsInteger = *addressOfXInterpretedAsInteger;

    printf("%.3f : 0x%08x\n", x, xInterpretedAsInteger);

    x = -0.0;
    printf("%.3f : 0x%08x\n", x, *((unsigned int *)(&x)));

    x = -32.0;
    y = 11.0;
    z = y / x;
    printf("%.3f : 0x%08x\n", z, *((unsigned int *)(&z)));

	// Repeating binary...
    x = 3.0;
    y = 1.0;
    z = y / x;
    printf("%.3f : 0x%08x\n", z, *((unsigned int *)(&z)));

	// Infinity
    x = 0.0;
    y = 1.0;
    z = y / x;
    printf("%.3f : 0x%08x\n", z, *((unsigned int *)(&z)));

	// Not a number!
    x = 0.0;
    y = 0.0;
    z = y / x;
    printf("%.3f : 0x%08x\n", z, *((unsigned int *)(&z)));

	// Mess with z and a big number
	printf("Begin David's weird idea\n");
	x = 0.0;
    y = 1.0;
    z = y / x; // z is now +inf
    unsigned int bigNumber = 0x7f7fffff;
    x = *((float *)&bigNumber);
    printf("%.3f : 0x%08x\n", x, bigNumber);
	y = z / x;
    printf("%.3f : 0x%08x\n", y, *((unsigned int *)(&y)));
	y = x / z;
    printf("%.3f : 0x%08x\n", y, *((unsigned int *)(&y)));
	printf("Done with David's weird idea\n");

    return 0;
}