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POHelp with C Pointers
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copied!<p>I have a query with regards to pointers, can someone help explain the following to me?</p> <p>I do understand how the pointers work, however, I ain't too sure as to how overwriting parts of memory from addresses modify the behavior of the program.</p> <p>I will explain the following as much as I can according to what I understand, feel free to critic and enlighten me on my misunderstandings, heres the code chunk:</p> <pre><code>void f(int) ; int main ( int argc, char ** argv ) { int a = 1234 ; f(a); printf("Back to main\n") ; } void g() { printf("Inside g\n") ; } void f (int x) { int a[100] ; memcpy((char*)a,(char*)g,399) ; x = *(&x-1) ; *(&x-1) = (int)(&a) ; // note the cast; no cast -&gt; error // find an index for a such that a[your_index] is the same as x printf("About to return from f\n") ; } //This program, compiled with the same compiler as above, produces the following output: //About to return from f //Inside g //Back to main </code></pre> <p>Ok from what I understand, this is how it goes.</p> <p>The program begin procedurally frorm main(), it assigns a, then goes into f() with a as variable.</p> <p>Inside f():</p> <p>It inits an array a of size 100. Then copies the memory space from g() to the entire a array. So now essentially a[] is g(). x is then assigned to the address of the original a from main() - 1, which I would assume is the address of main(). (I am not sure about this, correct me if I'm wrong)</p> <p>From here onwards, I ain't too sure how it manages to call a[] (the one that is overwritted with g()) or even g(). It just seems to end f() and go back to main().</p> <p>Thanks to whoever can help me out with this!</p> <p>Cheers!</p>

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