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    <p>The global variable <code>tuple</code> is the only actual <code>Tuple</code> in this program. Memory for global variables is managed by the compiler.</p> <p>In <code>main</code>, <code>Tuple *result</code> is just a pointer which, when you declared it, contains a random number (whatever happened to previously be in the space it now occupies) and thus <code>result</code> points to garbage (not a valid <code>Tuple</code> object).</p> <p>Then you assign the result of <code>findMaxSubArray</code> to <code>tuple</code>. Since <code>findMaxSubArray</code> returns <code>&amp;tuple</code> (in one way or another) which is a global variable, <code>result</code> points to the global variable <code>tuple</code>. So when you do <code>result-&gt;sum</code>, it's the same as doing <code>tuple.sum</code>.</p> <p>In <code>findMaxSubArray</code>, the line <code>Tuple *left, *right, *cross;</code> declares three pointers to <code>Tuple</code>s which contain a garbage value. In one branch of the <code>if</code> you don't use them and just return <code>&amp;tuple</code>, the address of the global variable <code>tuple</code>. In the other branch, you set <code>left</code>, <code>right</code>, and <code>cross</code> to either <code>findMaxCrossingSubArray</code> or <code>findMaxSubArray</code>, which both return <code>&amp;tuple</code> one way or the other.</p> <p>I do suggest reading a book on C++ and forgetting everything you know about C while using C++ (but remember it all again when you program C again). They are not the same language. This code is riddled with things you learned from your C training (such as <code>#define</code> and <code>typedef struct ... Tuple</code>) for which C++ offers better facilities.</p>
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    1. USSeth Carnegie
    1. USSeth Carnegie
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    1. COThanks for your reply, Seth. Like you said, those pointers(left, right and cross) contain garbage data in the first place. Later on, they are assigned to the address of global variable tuple. Since they are pointing to the same memory location, the comparison will end up falling into the else branch which happens to be the right case. If the if condition changes, my implementation will definitely have problem. I guess I could replace Tuple struct with a class in my implementation. Can you elaborate what are the c++ facilities I can use in my implementation? Thanks a lot.
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    2. CO@itnovice I think that you'd be better served by starting a new question and asking that there.
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