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POcrash if deleting char* member in destructor of an imbricated own container using vector
 

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  1. POcrash if deleting char* member in destructor of an imbricated own container using vector
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    <p>till then i used to cope, here i'm trying to build my own container class using vector. I need it for my work. I'm using <strong>codeblocks 10.05</strong></p> <pre><code>class myclass { public : vector&lt;myclass&gt; array; char * classname; ... </code></pre> <p>The problem is that my datum of my class is <strong>well displayed on screen if its deleting doesn't occur in the destructor.</strong> My function show() diplays odd characters if I delete classname. I suppose it to come from my method to build object and a matter of range when I pass them as argument.</p> <pre><code> myclass::~myclass() { //if(classname) delete [] classname; } </code></pre> <p>And this is how it is initialized in <strong>the constructor :</strong></p> <pre><code> myclass::myclass(long lvl = 0, const char name[] = "undefined") :ID(++ ID_counter) { level = lvl; int namelength = strlen(name); classname = new char[namelength + 1]; strcpy(classname, name); } </code></pre> <p><strong>add_content(const myclass &amp; c)</strong> is supposed to make a copy of teh elements of c.array and "push_back" them in this->array I find out per chance that we could put an object with no name as parameter : <strong>mycontainer.add_content(myclass(3,5));</strong> it works but i'm skeptic about the scope it should have</p> <pre><code>&gt; int main() &gt; { &gt; myclass mycontainer(0); &gt; mycontainer.add_content(myclass(3,5)); &gt; ... </code></pre> <p>Here is <strong>the full code :</strong></p> <pre><code>#include &lt;vector&gt; #include &lt;iostream&gt; using namespace std; class myclass { public : vector&lt;myclass&gt; array; static long ID_counter; long ID; long level; char * classname; myclass(int n, long lvl, const char name[]); //push_back n elements, lvl = 0, name = "undefined" myclass(long lvl, const char name[]); //lvl = 0, name = "undefined" myclass::~myclass(); void set_level(long lvl); //recursive function, go down the tree void add(int n); //push_back n elements void add(const myclass &amp; c); //push_back and set back the levels void add_content(const myclass &amp; c); //push_back all the c.array[i] and set back the levels void show(); template &lt;typename T&gt; myclass &amp; operator[](const T it){ return array[it]; } }; long myclass::ID_counter = 0; myclass::myclass(long lvl = 0, const char name[] = "undefined") :ID(++ ID_counter) { level = lvl; int namelength = strlen(name); classname = new char[namelength + 1]; strcpy(classname, name); } myclass::myclass(int n, long lvl, const char name[] = "undefined") :ID(++ ID_counter) { level = lvl; int namelength = strlen(name); classname = new char[namelength + 1]; strcpy(classname, name); for(int i = 0; i &lt; n; i++) array.push_back( myclass(this-&gt;level + 1) ); } myclass::~myclass() { //if(classname) delete [] classname; //there is the point ! } void myclass::add(int n = 1) { for(int i = 0; i &lt; n; i++) array.push_back( myclass(level + 1) ); } void myclass::add(const myclass &amp; c) { array.push_back(c); array[array.size() - 1].set_level(level + 1); } void myclass::add_content(const myclass &amp; c) { for(int i = 0; i &lt; c.array.size(); i++) { array.push_back(c.array[i]); array[array.size() - 1].set_level(level + 1); } } void myclass::set_level(long lvl) { level = lvl; for(int i = 0; i &lt; array.size(); i++) array[i].set_level(level + 1); } void myclass::show() { cout &lt;&lt; "ID : " &lt;&lt; ID &lt;&lt; "\tLvl : " &lt;&lt; level &lt;&lt; "\t Classname : " &lt;&lt; classname &lt;&lt; endl; } int main() { myclass mycontainer(0); //ground level mycontainer.add_content(myclass(3,5)); //the 3 elements level 5 should be reset to 0+1 mycontainer.show(); for(int i = 0; i &lt; mycontainer.array.size(); i++) { mycontainer[i].show(); for(int j= 0; j &lt; mycontainer[i].array.size(); j++) mycontainer[i][j].show(); } cout &lt;&lt; "\ncheckpoint\n"; system("PAUSE"); //press any key to crash! return 0; } </code></pre> <p>here <strong>no deletion of *classname in the destructor</strong>, the program rend this :</p> <pre><code>ID : 1 Lvl : 0 Classname : undefined ID : 3 Lvl : 1 Classname : undefined ID : 4 Lvl : 1 Classname : undefined ID : 5 Lvl : 1 Classname : undefined checkpoint Appuyez sur une touche pour continuer... </code></pre> <p><strong>with deletion</strong> and some bad characters show up with a crash:</p> <pre><code>ID : 1 Lvl : 0 Classname : undefined ID : 3 Lvl : 1 Classname : ░(? ID : 4 Lvl : 1 Classname : ░(? ID : 5 Lvl : 1 Classname : ░(? checkpoint Appuyez sur une touche pour continuer... Process returned -1073741819 (0xC0000005) execution time : 29.651 s Press any key to continue. </code></pre> <p>I tried to study back some principles about arguments and pointers but this language is too empirical and makes no sense. Thank you for helping.</p>
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    1. USnomatchland
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      1. POcrash if deleting char* member in destructor of an imbricated own container using vector
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    1. COPerhaps a review of [The Rule of Three](http://en.wikipedia.org/wiki/Rule_of_three_(C%2B%2B_programming)) may shed light on this, specifically for `myclass` (if that wasn't obvious).
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      1. POcrash if deleting char* member in destructor of an imbricated own container using vector
      1. USWhozCraig
 

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