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    <p><code>rand()</code> can be used to generate pseudo-random numbers in C++. In combination with <code>RAND_MAX</code> and a little math, you can generate random numbers in any arbitrary interval you choose. This is sufficient for learning purposes and toy programs. If you need <em>truly</em> random numbers with normal distribution, you'll need to employ a more advanced method.</p> <hr> <p>This will generate a number from 0.0 to 1.0, inclusive.</p> <pre><code>float r = static_cast &lt;float&gt; (rand()) / static_cast &lt;float&gt; (RAND_MAX); </code></pre> <p>This will generate a number from 0.0 to some arbitrary <code>float</code>, <code>X</code>:</p> <pre><code>float r2 = static_cast &lt;float&gt; (rand()) / (static_cast &lt;float&gt; (RAND_MAX/X)); </code></pre> <p>This will generate a number from some arbitrary <code>LO</code> to some arbitrary <code>HI</code>:</p> <pre><code>float r3 = LO + static_cast &lt;float&gt; (rand()) /( static_cast &lt;float&gt; (RAND_MAX/(HI-LO))); </code></pre> <hr> <p>Note that the <code>rand()</code> function will often not be sufficient if you need truly random numbers.</p> <hr> <p>Before calling <code>rand()</code>, you must first "seed" the random number generator by calling <code>srand()</code>. This should be done once during your program's run -- not once every time you call <code>rand()</code>. This is often done like this:</p> <pre><code>srand (static_cast &lt;unsigned&gt; (time(0))); </code></pre> <p>In order to call <code>rand</code> or <code>srand</code> you must <code>#include &lt;cstdlib&gt;</code>.</p> <p>In order to call <code>time</code>, you must <code>#include &lt;ctime&gt;</code>.</p>
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    1. POC++ random float number generation
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    1. USFlorin Mircea
    1. USJohn Dibling
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    1. CODon't forget to seed first!
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      1. USKlaim
    2. COBest to note that the both limits are inclusive.
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      1. USdmckee
    3. COAlso the system rand() is usually fairly primitive, and not a good idea for many applications---look at the many SO questions on random number generators for details...
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