/**
 * Program to show hexadecimal representation of ints and doubles.
 *
 * Attempts to be as portable as possible by using "union" data types 
 * to access data as array of unsigned characters (bytes).
 *
 * Also prints sizes of some things (to show how they can be different
 * on different systems).
 */
#include <stdio.h>

typedef union {
    int n;
    unsigned char chars[sizeof (int)];
} int_or_char;

typedef union {
    double d;
    unsigned char chars[sizeof (double)];
} double_or_char;

/*
 * print hexadecimal representation of array of chars
 * "size_t" here is an unsigned integer type big enough to hold sizes
 * of things.
 */
void print_chars_hex(unsigned char* chars, size_t num_chars) {
    for (size_t i = 0; i < num_chars; ++i) {
        printf("%.2hhx ", chars[i]);
    }
    printf("\n");
}

/* 
 * print hexadecimal representation of int
 */
void print_int_hex(int_or_char* int_data) {
    printf("int %d in hexadecimal is ", int_data->n);
    print_chars_hex(int_data->chars, sizeof int_data->n);
}

/* 
 * print hexadecimal representation of double
 */
void print_double_hex(double_or_char* double_data) {
    printf("double %g in hexadecimal is ", double_data->d);
    print_chars_hex(double_data->chars, sizeof double_data->d);
}

/* main program */
int main(void) {

    int_or_char int_data;
    double_or_char double_data;

    printf("sizeof int is %zd\n", sizeof(int));
    printf("sizeof short is %zd\n", sizeof(short));
    printf("sizeof long is %zd\n", sizeof(long));
    printf("sizeof size_t is %zd\n", sizeof(size_t));
    printf("sizeof float is %zd\n", sizeof(float));
    printf("sizeof double is %zd\n", sizeof(double));
    printf("\n");

    printf("enter floating-point values, anything else to end:\n");
    while (scanf("%lg", &(double_data.d)) == 1) {
        int_data.n = (int) double_data.d;
        print_int_hex(&int_data);
        print_double_hex(&double_data);
    }
    return 0;
}