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copied!<p>Dereferencing a character pointer got you the first character-sized chunk of the internal representation of 1000 as an integer. That character was then promoted to a <code>int</code> (as per the rules for varidac arguments), and interpreted as integer.</p> <p>On you machine, with that compiler, the result was -24.</p> <p>Character sized chunk was <em>probably</em> a 8-bit byte.</p> <p>The integer was <em>probably</em> represented by 4 or 8 of those bytes.</p> <p>The internal representation was <em>probably</em> 2s-complement, and was <em>probably</em> stored in little endian order.</p> <p>Do you begin to see why the result wasn't easy for you to predict?</p> <hr> <p>Doing the same thing with a float pointer returned a <code>float</code> sized chuck of memory instead of a <code>char</code>, and now you may have <em>real</em> (heh!) trouble because we don't know, at this point if the <code>float</code> representation will even fit in a <code>int</code> representation, so you may be accessing uninitialized memory.</p> <p>In any case, when you dereferenced the <code>float*</code> it interpreted that memory as <code>float</code> (which has a rather more complex internal structure than a character or even a 2s-complement integer), and promoted it to a <code>double</code> (those rules for varidac arguments again) <em>then</em> an attempt was made interpret that representation as an integer (and if the <code>float</code> <em>did</em> fit in an <code>int</code>, the <code>double</code> probably <em>doesn't</em>, so you're interpreting <em>part</em> of the double as an int!). Ugh.</p> <p>This situation is even worse than the last because it involves the IEEE floating point representation standards and two chances to have the sizes not match up at all.</p> <p>So the lesson here is:</p> <h2>Don't do that.</h2> <p>And the subsidiary lesson, only for experts is</p> <h2>Still don't do it.</h2> <p>because if you want to perform all these silly reinterpretations you want to have exact and explicit control of them.</p>

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