/*
    floatingpoint.c
	Jeff Ondich
	Last updated 22 April 2019

	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!
*/
#include <stdio.h>

unsigned int floatAsUnsignedInt(float x);
void printFloatAsInt(float x);
float intAsFloat(unsigned int n);
void printIntAsFloat(unsigned int n);

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

    x = -12.5;
    printFloatAsInt(x);
    unsigned int k = floatAsUnsignedInt(x);
    printIntAsFloat(k);

    x = -0.0;
    printFloatAsInt(x);

    x = -16.0;
    y = 5.0;
    z = y / x;
    printFloatAsInt(x);

	// Repeating binary...
    x = 6.0;
    y = 23.0;
    z = y / x;
    printFloatAsInt(x);

	// Infinity
    x = 0.0;
    y = 1.0;
    z = y / x;
    printFloatAsInt(x);

	// Not a number!
    x = 0.0;
    y = 0.0;
    z = x / y;
    printFloatAsInt(z);

    return 0;
}

// Utility functions
unsigned int floatAsUnsignedInt(float x) {
    float *addressOfX = &x;
    unsigned int *addressOfXInterpretedAsInteger
            = (unsigned int *)addressOfX;
    unsigned int xInterpretedAsInteger
            = *addressOfXInterpretedAsInteger;
    return xInterpretedAsInteger;
}

void printFloatAsInt(float x) {
    printf("%.3f : 0x%08x\n", x, floatAsUnsignedInt(x));
}

float intAsFloat(unsigned int n) {
    unsigned int *addressOfN = &n;
    float *addressOfNInterpretedAsFloat = (float *)addressOfN;
    float nInterpretedAsFloat = *addressOfNInterpretedAsFloat;
    return nInterpretedAsFloat;
}

void printIntAsFloat(unsigned int n) {
    printf("0x%08x : %.3f\n", n, intAsFloat(n));
}