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POWhen using calloc in C what is stored at the address of the pointer?
 

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  1. POWhen using calloc in C what is stored at the address of the pointer?
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    <p>I'm having a hard time understanding this program to illustrate pointers (from <a href="http://theocacao.com/document.page/234" rel="nofollow">http://theocacao.com/document.page/234</a>):</p> <p>Below I don't understand why:</p> <pre><code>int * currentSlot = memoryBlock </code></pre> <p>isn't using <code>&amp;memoryBlock</code>. I read the comment but don't get it. What is memoryBlock putting in there that &amp;memoryBlock wouldn't? Won't both return the pointer to the set of ints created with calloc (assuming I understand what's been done that is)? What is really in <code>* memoryBlock</code> after <code>calloc</code>?</p> <p>Then here, <code>*currentSlot = rand();</code>, how does the dereferencing work here? I thought the dereference would stop *currentSlot from giving the value of the memory address (the reference) to the actual value (no longer a reference but the value).</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; // for calloc and free #include &lt;time.h&gt; // for random seeding main () { const int count = 10; int * memoryBlock = calloc ( count, sizeof(int) ); if ( memoryBlock == NULL ) { // we can't assume the memoryBlock pointer is valid. // if it's NULL, something's wrong and we just exit return 1; } // currentSlot will hold the current "slot" in the, // array allowing us to move forward without losing // track of the beginning. Yes, C arrays are primitive // // Note we don't have to do '&amp;memoryBlock' because // we don't want a pointer to a pointer. All we // want is a _copy_ of the same memory address int * currentSlot = memoryBlock; // seed random number so we can generate values srand(time(NULL)); int i; for ( i = 0; i &lt; count; i++ ) { // use the star to set the value at the slot, // then advance the pointer to the next slot *currentSlot = rand(); currentSlot++; } // reset the pointer back to the beginning of the // memory block (slot 0) currentSlot = memoryBlock; for ( i = 0; i &lt; count; i++ ) { // use the star to get the value at this slot, // then advance the pointer printf("Value at slot %i: %i\n", i, *currentSlot); currentSlot++; } // we're all done with this memory block so we // can free it free( memoryBlock ); } </code></pre> <p>Thank you for any help.</p>
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