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POEXC_BAD_ACCESS when passing a pointer-to-pointer in a struct?
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  1. POEXC_BAD_ACCESS when passing a pointer-to-pointer in a struct?
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    copied!<p>I've got a c-array of CGPoints in a struct. I need to replace this array when another CGPoint is added. I'd swear I'm doing this right and it seems to work fine a few times but eventually I'll get a <code>EXC_BAD_ACCESS</code>. What am I missing?</p> <p>Here's the struct, which I've truncated to remove a lot of items that don't pertain.</p> <pre><code>typedef struct{ CGPoint **focalPoints; NSUInteger focalPointCount; CGRect boundingRect; }FocalPoints; </code></pre> <p>Here's how I initialize it:</p> <pre><code>CGPoint *fPoints = (CGPoint *)malloc(sizeof(CGPoint)); FocalPoints focalInfo = {&amp;fPoints, 0, rect}; </code></pre> <p>Note that <code>focalInfo</code> is passed by reference to another function, like so: <code>anotherFunction(&amp;focalInfo)</code>.</p> <p>Now here's the function that replaces the Points array with a new one:</p> <pre><code>void AddFocalPoint (CGPoint focalPoint, FocalPoints *focal){ if (focalPoint.x == CGFLOAT_MAX) return; if (!CGRectContainsPoint(focal-&gt;boundingRect, focalPoint)) return; int origCount = focal-&gt;focalPointCount; int newCount = origCount + 1; CGPoint *newPoints = (CGPoint *) malloc((newCount) * sizeof(CGPoint)); for (int i = 0; i &lt; newCount; i++) newPoints[i] = (i &lt; origCount) ? *focal-&gt;focalPoints[i] : focalPoint; //error occurs here free(*focal-&gt;focalPoints); *focal-&gt;focalPoints = newPoints; focal-&gt;focalPointCount = newCount; } </code></pre> <p>The EXC_BAD_ACCESS error occurs in the above code on line 8: <code>newPoints[i] = (i &lt; origCount) ? *focal-&gt;focalPoints[i] : focalPoint;</code>. So what exactly am I doing wrong?</p>
 

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