#include <stdio.h>
#include <math.h>
#include <ctype.h>

unsigned short getRed(unsigned long);
unsigned short getGreen(unsigned long);
unsigned short getBlue(unsigned long);
void makeHCC(unsigned long r, unsigned long g, unsigned long b, char hex[]);
void makeHex(unsigned long n, char hex[]);

int main() {

  unsigned long num, combo;
  unsigned short red, green, blue;
  unsigned short cred=0, cgreen=0, cblue=0;
  char chex[8];

  const unsigned long MAX = pow(2,32)-1;
  char ch;

  //  printf("sizeof(num) is %ld and MAX is %ld\n", sizeof(num), MAX);
  puts("enter three integers between 0 and 2^32 - 1");

  ch = getchar();
  // repeat three times
  for (int count = 1; count <= 3; count++) {
	// read num
	if (! isdigit(ch))  // bad input
	  return 1;

	num = 0;
	while (isdigit(ch)) {
	  num = num * 10 + ch - '0';
	  ch = getchar();
	}
	if (count < 3)
	  while (isspace(ch)) {
		ch = getchar();
	  }

	if (num > MAX)  // bad input
	  return 2;

	red = getRed(num);
	green = getGreen(num);
	blue = getBlue(num);
	printf("num is %ld == rgb(%d, %d, %d) (for testing: == #%08lx)\n", 
		   num, red, green, blue, num);

	if (count == 1)
	  cred = red;
	if (count == 2)
	  cgreen = green;
	if (count == 3)
	  cblue = blue;
  
  } // for each number

  combo = (((cred << 8) + cgreen) << 8) + cblue;
  makeHex(combo, chex);
  //  makeHCC(cred, cgreen, cblue, chex);
  printf("combo color is rgb(%d, %d, %d) == %s == %ld\n", 
		 cred, cgreen, cblue, chex, combo);

  return 0;
}


unsigned short getRed(unsigned long n) {
  //  n = n & 0x00FF0000;  // mask the red bits
  // return (unsigned short) (n >> 16);
  n = n >> 16;
  n = n & 0x000000FF;
  return (unsigned short) n;
}

unsigned short getGreen(unsigned long n) {
  n = n >> 8;
  n = n & 0x000000FF;  // mask the green bits
  return (unsigned short) n;
}

unsigned short getBlue(unsigned long n) {
  n = n & 0x000000FF;  // mask the blue bits
  return (unsigned short) n;
}

void makeHex(unsigned long n, char hex[]) {
  sprintf(hex,"#%06lx", n);
}

void makeHCC(unsigned long r, unsigned long g, unsigned long b, char hex[]) {
  char color[3];
  hex[0] = '#';
  sprintf(color, "%02lx", r);
  hex[1] = color[0];
  hex[2] = color[1];
  sprintf(color, "%02lx", g);
  hex[3] = color[0];
  hex[4] = color[1];
  sprintf(color, "%02lx", b);
  hex[5] = color[0];
  hex[6] = color[1];
  hex[7] = '\0';
}