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    <h2>Why <code>rand</code> is a bad idea</h2> <p>Most of the answers you got here make use of the <code>rand</code> function and the modulus operator. That method <a href="http://channel9.msdn.com/Events/GoingNative/2013/rand-Considered-Harmful">may not generate numbers uniformly</a> (it depends on the range and the value of <code>RAND_MAX</code>), and is therefore discouraged.</p> <h2>C++11 and generation over a range</h2> <p>With C++11 multiple other options have risen. One of which fits your requirements, for generating a random number in a range, pretty nicely: <a href="http://en.cppreference.com/w/cpp/numeric/random/uniform_int_distribution"><code>std::uniform_int_distribution</code></a>. Here's an example:</p> <pre><code>const int range_from = 0; const int range_to = 10; std::random_device rand_dev; std::mt19937 generator(rand_dev()); std::uniform_int_distribution&lt;int&gt; distr(range_from, range_to); std::cout &lt;&lt; distr(generator) &lt;&lt; '\n'; </code></pre> <p>And <a href="http://coliru.stacked-crooked.com/a/c5b94870fdcd13f2">here</a>'s the running example.</p> <h3>Other random generators</h3> <p>The <a href="http://en.cppreference.com/w/cpp/numeric/random"><code>&lt;random&gt;</code> header</a> offers innumerable other random number generators with different kind of distributions including Bernoulli, Poisson and normal.</p> <h3>How can I shuffle a container?</h3> <p>The standard provides <a href="http://en.cppreference.com/w/cpp/algorithm/random_shuffle"><code>std::random_shuffle</code></a>, which can be used as follows:</p> <pre><code>std::vector&lt;int&gt; vec = {4, 8, 15, 16, 23, 42}; std::random_device random_dev; std::mt19937 generator(random_dev()); std::shuffle(vec.begin(), vec.end(), generator); </code></pre> <p>The algorithm will reorder the elements randomly, with a linear complexity.</p> <h2>Boost.Random</h2> <p>Another alternative, in case you don't have access to a C++11+ compiler, is to use <a href="http://www.boost.org/doc/libs/1_55_0/doc/html/boost_random.html">Boost.Random</a>. Its interface is very similar to the C++11 one.</p>
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