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POTest if multiple variable values are either all positive or negative
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  1. POTest if multiple variable values are either all positive or negative
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    copied!<p>Is there a good and fast way in <strong>C/C++</strong> to test if multiple variables contains either all positive or all negative values?</p> <p>Say there a 5 variables to test:</p> <p><strong>Variant 1</strong></p> <pre><code>int test(int a[5]) { if (a[0] &lt; 0 &amp;&amp; a[1] &lt; 0 &amp;&amp; a[2] &lt; 0 &amp;&amp; a[3] &lt; 0 &amp;&amp; a[4] &lt; 0) { return -1; } else if (a[0] &gt; 0 &amp;&amp; a[1] &gt; 0 &amp;&amp; a[2] &gt; 0 &amp;&amp; a[3] &gt; 0 &amp;&amp; a[4] &gt; 0) { return 1; } else { return 0; } } </code></pre> <p><strong>Variant 2</strong></p> <pre><code>int test(int a[5]) { unsigned int mask = 0; mask |= (a[0] &gt;&gt; numeric_limits&lt;int&gt;::digits) &lt;&lt; 1; mask |= (a[1] &gt;&gt; numeric_limits&lt;int&gt;::digits) &lt;&lt; 2; mask |= (a[2] &gt;&gt; numeric_limits&lt;int&gt;::digits) &lt;&lt; 3; mask |= (a[3] &gt;&gt; numeric_limits&lt;int&gt;::digits) &lt;&lt; 4; mask |= (a[4] &gt;&gt; numeric_limits&lt;int&gt;::digits) &lt;&lt; 5; if (mask == 0) { return 1; } else if (mask == (1 &lt;&lt; 5) - 1) { return -1; } else { return 0; } } </code></pre> <p><strong>Variant 2a</strong></p> <pre><code>int test(int a[5]) { unsigned int mask = 0; for (int i = 0; i &lt; 5; i++) { mask &lt;&lt;= 1; mask |= a[i] &gt;&gt; numeric_limits&lt;int&gt;::digits; } if (mask == 0) { return 1; } else if (mask == (1 &lt;&lt; 5) - 1) { return -1; } else { return 0; } } </code></pre> <p>What Version should I prefer? Is there any adavantage using variant 2/2a over 1? Or is there a better/faster/cleaner way?</p>
 

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