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POWhy can't I reclaim my dynamically allocated memory using the "delete" keyword?
 

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  1. POWhy can't I reclaim my dynamically allocated memory using the "delete" keyword?
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    <p>I have the following class:</p> <pre><code>class Patient { public: Patient(int x); ~Patient(); private: int* RP; }; Patient::Patient(int x) { RP = new int [x]; } Patient::~Patient() { delete [] RP; } </code></pre> <p>I create an instance of this class on the stack as follows:</p> <pre><code>void f() { Patient p(10); } </code></pre> <p>Now, when <code>f()</code> returns, I get a "double free or corruption" error, which signals to me that something is attempted to be deleted more than once. But I don't understand why that would be so. The space for the array is created on the heap, and just because the function from inside which the space was allocated returns, I wouldn't expect the space to be reclaimed.</p> <p>I thought that if I allocate space on the heap (using the <code>new</code> keyword), then the only way to reclaim that space is to use the delete keyword. Help!</p> <p><strong>As requested, here is the actual code (slightly abridged for brevity's sake)</strong></p> <p>Here's the full class definition (split across a <code>.cpp</code> and <code>.h</code> file, but shown together):</p> <pre><code>class Patient { public: Patient(int numDecisionEpochs); ~Patient(); void recordRP(const int&amp; age, const bool&amp; t); void recordBiopsy(const int&amp; age, const int&amp; result); void recordPSA(const int&amp; age, const double&amp; level); void recordPSA(const int&amp; age); private: int* RP; int* Biopsy; double* PSA; }; Patient::Patient(int numDecisionEpochs) { RP = new int [numDecisionEpochs]; Biopsy = new int [numDecisionEpochs]; PSA = new double [numDecisionEpochs]; } Patient::~Patient() { delete[] RP; } void Patient::recordRP(const int&amp; age, const bool&amp; t) { if(t) RP[age-1] = 1; // RP either yes (1) or no (0) else RP[age-1] = 0; } void Patient::recordBiopsy(const int&amp; age, const int&amp; result) { switch(result) { case 0: case 1: case 2: case 3: case 4: Biopsy[age-1]=result; // only permit results 0,1,2,3,4 break; default: cerr &lt;&lt; "Invalid biopsy result (" &lt;&lt; result &lt;&lt; ") at age " &lt;&lt; age &lt;&lt; "!\n"; } } void Patient::recordPSA(const int&amp; age, const double&amp; level) { PSA[age-1] = level; // record PSA volume } void Patient::recordPSA(const int&amp; age) { PSA[age-1] = -1; // symbol for no screening during epoch } </code></pre> <p>Next, the function where the above class is used. The following function is called directly from <code>main()</code> and passed a <code>Policy</code> object which is completely independent and separate from the <code>Patient</code> class:</p> <pre><code>void simulate1(Policy&amp; P) { // ... Patient patient(260); for(int idx=0; idx&lt;(P.size); idx++) { while(state != 9) // while patient not dead { // ... patient.recordPSA(age,PSA); // ... patient.recordPSA(age); // ... patient.recordBiopsy(age,biopsyResult); // ... patient.recordRP(age,true); // ... patient.recordRP(age,false); // ... } // end patient (while loop) } // end sample (for loop) } // end function </code></pre>
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      1. POWhy can't I reclaim my dynamically allocated memory using the "delete" keyword?
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      1. POWhy can't I reclaim my dynamically allocated memory using the "delete" keyword?
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    1. COYour code runs fine: http://ideone.com/Gw2QM. And technically `delete` is not guaranteed to reclaim any space, it's possible you could have a `new` and `delete` implementation that just keep on allocating memory pages.
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