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POHow to correctly deallocate a c++ vector?
 

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  1. POHow to correctly deallocate a c++ vector?
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    <blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/8546239/how-to-correctly-deallocate-or-delete-a-c-vector">How to correctly deallocate or delete a c++ vector?</a> </p> </blockquote> <p>I'm having some problems trying to delete memory that I've allocated in a vector. Even though I call list.clear(), it's not deallocating the memory.</p> <p>So I have some code like this in a template-based class called Set</p> <pre><code>template &lt;class T&gt; class Set { public: // stuff private: int size; std::vector&lt;T&gt; list; }; </code></pre> <p>And in the constructor, I have allocated memory for the vector. So I call list = new std::vector;</p> <p>For your interest, here is my copy constructor and assignment operator that I've also witten where I also allocate memory for the vector:</p> <pre><code>template &lt;class T&gt; Set&lt;T&gt;::Set(const Set&amp; aSet) { size = aSet.size; list-&gt;clear(); list = new vector&lt;T&gt;; for (int i = 0; i &lt; size; ++i) { list[i] = aSet.list[i]; } } template &lt;class T&gt; Set&lt;T&gt;&amp; Set&lt;T&gt;::operator=(const Set&amp; right) { if (this != &amp;right) { list-&gt;clear(); size = right.size; list = new vector&lt;T&gt;; for (int i = 0; i &lt; size; ++i) { list[i] = right.list[i]; } } return (*this); } </code></pre> <p>In the destructor, I just have list.clear() to delete all elements and then deallocate the memory.</p> <p>But the problem is, when I run valgrind on my .out file, it's telling me that I've definitely lost some memory and I don't know why it's telling me this. I've read some questions here on Stackoverflow but I've basically tried everything. I tried clear() and then delete on the vector but that didn't work. I then tried to erase(list.begin(), list.end()) but that didn't work too. </p> <p>My thought process is that I'm using a Set *aSet = new Set; in my main class and since an int is not an object, it's not being freed when I call list.clear(). Is this right? How would I go about deleting the memory correctly?</p> <p>Thanks for any help. </p> <p>Edit1 = changed list* to setList</p> <p>My new constructors and the assignment operator:</p> <pre><code>template &lt;class T&gt; Set&lt;T&gt;::Set(const Set&amp; aSet) { size = aSet.size; setList.clear(); setList = aSet.setList; } template &lt;class T&gt; Set&lt;T&gt;&amp; Set&lt;T&gt;::operator=(const Set&amp; right) { if (this != &amp;right) { setList.clear(); size = right.size; setList = right.setList; } return (*this); } </code></pre> <p>Valgrind still reports I have the same amount of lost memory though. In my destructor I still have list.clear()</p> <p>Valgrind log:</p> <pre><code>==11398== ==11398== HEAP SUMMARY: ==11398== in use at exit: 62,969 bytes in 352 blocks ==11398== total heap usage: 540 allocs, 188 frees, 68,046 bytes allocated ==11398== ==11398== LEAK SUMMARY: ==11398== definitely lost: 8,624 bytes in 14 blocks ==11398== indirectly lost: 1,168 bytes in 5 blocks ==11398== possibly lost: 4,829 bytes in 56 blocks ==11398== still reachable: 48,348 bytes in 277 blocks ==11398== suppressed: 0 bytes in 0 blocks ==11398== Rerun with --leak-check=full to see details of leaked memory </code></pre>
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    1. COKill the whole pointer and `new` business.
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      1. POHow to correctly deallocate a c++ vector?
      1. USchris
    2. COwhy not use vector by value? Also, are you trying to create a std::set on your own? Do you know about destructors?
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      1. POHow to correctly deallocate a c++ vector?
      1. USDmitry Ledentsov
    3. COEvery `new` needs a matching `delete`. `clear()` removes all elements from the vector, and does not affect the memory of the vector object itself.
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      1. POHow to correctly deallocate a c++ vector?
      1. USCameron
 

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