On-Demand Random Number Generator

main.cpp

#include <iostream>
using namespace std;

/* On-Demand Random Number Generator */
#include "Random.h"

int main() {

	/* Randomize seed */
	Random::randomize();
	
	/* Number range: 91 <= value < 123 */
	Random random(97, 123);

	/* Numbers */
	int number;

	for (int i = 0; i < 3; ++i) {
		number = random;
		cout << number << endl;
	}

	/* Characters */
	char character;

	for (int i = 0; i < 3; ++i) {
		character = random;
		cout << character << endl;
	}

	/* Direct output needs explicit casting */
	for (int i = 0; i < 3; ++i)
		cout << (int) random << endl;

	/* Done. */
	return 0;
}

Random.h

/* On-Demand Random Number Generator
 *
 * (C) Copyright 2010, Mauricio Faria de Oliveira
 * http://mfoliveira.org
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#ifndef MFOLIVEIRA_RANDOM_H
#define MFOLIVEIRA_RANDOM_H

#include <cstdlib>
#include <ctime>

class Random {

protected:

	/* Base Value:
	 * all random numbers >= base */
	int base;

	/* Limit Value:
	 * all random numbers < limit */
	int limit;

public:

	/* Constructor */
	Random(int base = 0, int limit = 0) {

		/* Initialization */
		this->base  = base;
		this->limit = limit;
	}

	/* Seed Randomizer */
	static void randomize() {

		/* Initialize seed based on current time */
		srand(std::time(0));
	}

	/* Cast Operator overload */
	template <typename T>
	operator T() {

		/* Arbitrarily casting to type T.
		 * This returns 1 <= sizeof(T) <= sizeof(int) random bytes. ;-) */
		if (0 == limit)
			return static_cast<T>
				(base + std::rand());

		else
			return static_cast<T>
				(base + std::rand() % (limit - base));
	}

};

#endif // MFOLIVEIRA_RANDOM_H