61 lines
1.9 KiB
C++
61 lines
1.9 KiB
C++
// die.cpp
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//
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// Copyright (c) 2009
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// Steven Watanabe
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//[die
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/*`
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For the source of this example see
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[@boost://libs/random/example/die.cpp die.cpp].
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First we include the headers we need for __mt19937
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and __uniform_int_distribution.
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*/
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#include <boost/random/mersenne_twister.hpp>
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#include <boost/random/uniform_int_distribution.hpp>
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/*`
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We use __mt19937 with the default seed as a source of
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randomness. The numbers produced will be the same
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every time the program is run. One common method to
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change this is to seed with the current time (`std::time(0)`
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defined in ctime).
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*/
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boost::random::mt19937 gen;
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/*`
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[note We are using a /global/ generator object here. This
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is important because we don't want to create a new [prng
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pseudo-random number generator] at every call]
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*/
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/*`
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Now we can define a function that simulates an ordinary
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six-sided die.
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*/
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int roll_die() {
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/*<< __mt19937 produces integers in the range [0, 2[sup 32]-1].
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However, we want numbers in the range [1, 6]. The distribution
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__uniform_int_distribution performs this transformation.
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[warning Contrary to common C++ usage __uniform_int_distribution
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does not take a /half-open range/. Instead it takes a /closed range/.
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Given the parameters 1 and 6, __uniform_int_distribution
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can produce any of the values 1, 2, 3, 4, 5, or 6.]
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>>*/
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boost::random::uniform_int_distribution<> dist(1, 6);
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/*<< A distribution is a function object. We generate a random
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number by calling `dist` with the generator.
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>>*/
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return dist(gen);
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}
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//]
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#include <iostream>
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int main() {
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for(int i = 0; i < 10; ++i) {
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std::cout << roll_die() << std::endl;
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}
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}
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