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  1. POglibc detected *** ./a.out: munmap_chunk(): invalid pointer:
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    copied!<p>There are many questions like this but after looking at some cases, I guess this question is case-specific so I post my code and pointed out where the problem takes place may you be patient reading my code?</p> <h3>uniBTree.h</h3> <pre><code>#ifndef uniBTree_H #define uniBTree_H #include "uniTreeNode.h" #include &lt;cassert&gt; template&lt;class T&gt; class uniBTree { private: uniTreeNode&lt;T&gt; *root; int delete_helper(uniTreeNode&lt;T&gt; *); uniTreeNode&lt;T&gt; *insert_helper(uniTreeNode&lt;T&gt; *, const T); void in_print_helper(const uniTreeNode&lt;T&gt; *) const; void pre_print_helper(const uniTreeNode&lt;T&gt; *) const; void post_print_helper(const uniTreeNode&lt;T&gt; *) const; public: uniBTree(void); uniBTree(uniTreeNode&lt;T&gt; *r); ~uniBTree(void); void insert(const T i); void in_print(void) const; void pre_print(void) const; void post_print(void) const; }; template&lt;class T&gt; uniBTree&lt;T&gt;::uniBTree(void) { root = NULL; } template&lt;class T&gt; uniBTree&lt;T&gt;::uniBTree(uniTreeNode&lt;T&gt; *r) { root = r; } template&lt;class T&gt; int uniBTree&lt;T&gt;::delete_helper(uniTreeNode&lt;T&gt; *n) { int count = 0; if (n == NULL) return 0; count += delete_helper(n-&gt;get_left()); count += delete_helper(n-&gt;get_right()); delete n; count++; return count; } template&lt;class T&gt; uniBTree&lt;T&gt;::~uniBTree(void) { int count = delete_helper(root); std::cout &lt;&lt; "uniBTree&lt;T&gt;::~uniBTree&lt;T&gt;(void)\n"; std::cout &lt;&lt; count &lt;&lt; " nodes deleted\n"; } template&lt;class T&gt; void uniBTree&lt;T&gt;::in_print() const { in_print_helper(root); } template&lt;class T&gt; void uniBTree&lt;T&gt;::pre_print() const { pre_print_helper(root); } template&lt;class T&gt; void uniBTree&lt;T&gt;::post_print() const { post_print_helper(root); } template&lt;class T&gt; void uniBTree&lt;T&gt;::in_print_helper(const uniTreeNode&lt;T&gt; *current) const { if (current == NULL) return; in_print_helper(current-&gt;get_left()); current-&gt;print(); in_print_helper(current-&gt;get_right()); } template&lt;class T&gt; void uniBTree&lt;T&gt;::pre_print_helper(const uniTreeNode&lt;T&gt; *current) const { if (current == NULL) return; current-&gt;print(); pre_print_helper(current-&gt;get_left()); pre_print_helper(current-&gt;get_right()); } template&lt;class T&gt; void uniBTree&lt;T&gt;::post_print_helper(const uniTreeNode&lt;T&gt; *current) const { if (current == NULL) return; post_print_helper(current-&gt;get_left()); post_print_helper(current-&gt;get_right()); current-&gt;print(); } template&lt;class T&gt; void uniBTree&lt;T&gt;::insert(const T i) { if (root == NULL) root = new uniTreeNode&lt;T&gt;(i, NULL, NULL); else insert_helper(root, i); } template&lt;class T&gt; uniTreeNode&lt;T&gt; *uniBTree&lt;T&gt;::insert_helper(uniTreeNode&lt;T&gt; *current, const T i) { if (current == NULL) {//this is will only dealed by attempting to visit leaves... //if root is null, it'll be handled in insert uniTreeNode&lt;T&gt; *child = new uniTreeNode&lt;T&gt;(i, NULL, NULL); assert(child != NULL); return(child); } if (i &lt; current-&gt;get_data()) current-&gt;set_left(insert_helper(current-&gt;get_left(), i)); else current-&gt;set_right(insert_helper(current-&gt;get_right(), i)); return(current); } #endif </code></pre> <h3>uniTreeNode.h</h3> <pre><code>#ifndef uniTreeNode_H//for redefinition #define uniTreeNode_H #include &lt;iostream&gt; //using namespace std; don't use using namespace xxx and include source file in .h file template&lt;typename T&gt; class uniTreeNode { private: T data; uniTreeNode&lt;T&gt; *left; uniTreeNode&lt;T&gt; *right; public: //uniTreeNode&lt;T&gt;(void); uniTreeNode(T d, uniTreeNode&lt;T&gt; *l, uniTreeNode&lt;T&gt; *r); T get_data(void) const; uniTreeNode&lt;T&gt; *get_left(void) const; uniTreeNode&lt;T&gt; *get_right(void) const; void set_left(uniTreeNode&lt;T&gt; *l); void set_right(uniTreeNode&lt;T&gt; *r); void print() const; }; template&lt;typename T&gt; uniTreeNode&lt;T&gt;::uniTreeNode/*remember syntax here*/ (T d , uniTreeNode&lt;T&gt; *l = NULL, uniTreeNode&lt;T&gt; *r = NULL) { data = d; left = l; right = r; } template&lt;typename T&gt; T uniTreeNode&lt;T&gt;::get_data(void) const { return data; } template&lt;typename T&gt; uniTreeNode&lt;T&gt; * uniTreeNode&lt;T&gt;::get_left(void) const { return left; } template&lt;typename T&gt; uniTreeNode&lt;T&gt; * uniTreeNode&lt;T&gt;::get_right(void) const { return right; } template&lt;typename T&gt; void uniTreeNode&lt;T&gt;::set_left(uniTreeNode&lt;T&gt; *l) { left = l; } template&lt;typename T&gt; void uniTreeNode&lt;T&gt;::set_right(uniTreeNode&lt;T&gt; *r) { right = r; } template&lt;typename T&gt; void uniTreeNode&lt;T&gt;::print() const { std::cout &lt;&lt; "data is " &lt;&lt; data &lt;&lt; std::endl; } #endif </code></pre> <h3>date.h</h3> <pre><code>#include &lt;ostream&gt; class date{ private: int y; int m; int d; public: date();//default constructor date(const long int);//used by cplr as convert constructor date(int, int , int); friend bool operator&lt;(const date &amp;d1, const date &amp;d2);//d1 is for left-hand date friend bool operator&gt;(const date &amp;d1, const date &amp;d2); bool operator==(date d); bool operator!=(date d); date &amp;operator=(date d); friend std::ostream &amp;operator&lt;&lt;(std::ostream &amp;out, date d); friend std::istream &amp;operator&gt;&gt;(std::istream &amp;in, date d); }; </code></pre> <h3>date.cc</h3> <pre><code>#include &lt;iostream&gt; #include &lt;cstdio&gt; #include &lt;time.h&gt; #include &lt;cstring&gt; #include "date.h" date::date(){ y = m = d = 0; } date::date(int Y, int M, int D){ y = Y; m = M; d = D; } date::date(const long int s){//#second since 1970/1/1 00:00:00 struct tm *buf; buf = gmtime(&amp;s); y = (buf-&gt;tm_year+1900); m = buf-&gt;tm_mon+1; d = buf-&gt;tm_mday; } bool operator&lt;(const date &amp;d1, const date &amp;d2){ bool result;//sizeof(bool) is 1 if(d1.y &lt; d2.y) result = true; else if(d1.y == d2.y){ if(d1.m &lt; d2.m) result = true; else if(d1.m == d2.m){ if(d1.d &lt; d2.d) result = true; else result = false; } else result = false; } else result = false; return result; } bool operator&gt;(const date &amp;d1, const date &amp;d2){ bool result;//sizeof(bool) is 1 if(d1.y &gt; d2.y) result = true; else if(d1.y == d2.y){ if(d1.m &gt; d2.m) result = true; else if(d1.m == d2.m){ if(d1.d &gt; d2.d) result = true; else result = false; } else result = false; } else result = false; return result; } bool date::operator==(date d){ return (this-&gt;y==d.y &amp;&amp; this-&gt;m==d.m &amp;&amp; this-&gt;d==d.d); } bool date::operator!=(date d){ return (this-&gt;y!=d.y || this-&gt;m!=d.m || this-&gt;d!=d.d); } date &amp;date::operator=(date d){ this-&gt;y = d.y; this-&gt;m = d.m; this-&gt;d = d.d; return *this; } std::ostream &amp;operator&lt;&lt;(std::ostream &amp;out, date d){ out &lt;&lt; d.y &lt;&lt; "/" &lt;&lt; d.m &lt;&lt; "/" &lt;&lt; d.d &lt;&lt; std::endl; return out; } std::istream &amp;operator&gt;&gt;(std::istream &amp;in, date d){ in &gt;&gt; d.y &gt;&gt; d.m &gt;&gt; d.d ; return in; } </code></pre> <h3>main function</h3> <pre><code>#include "uniBTree.h" #include "date.h" #include &lt;cstdio&gt; int main(){ date d1 = 100000000;//convert constructor uniTreeNode&lt;date&gt; node(d1, NULL, NULL); printf("%p %p\n", node.get_left(), node.get_right()); std::cout &lt;&lt; node.get_data() &lt;&lt; std::endl; date d2 = 86401; date d3 = 200000000; uniBTree&lt;date&gt; btree(&amp;node); return 0; } </code></pre> <p>I tested and found that its <code>&amp;node</code> that is invalid. I think it is because it tries to "release" <code>btree</code> at the end of the program and when the root is encountered, because it points to <code>node</code>, it can't perform good thing.</p> <p>I have two question:</p> <ol> <li>if construct a <code>node</code> like what I did,(<code>uniTreeNode&lt;date&gt; node(xxx, xxx, xxx);</code>) was the object "NEW"ed by the program?</li> <li>for the <code>uniTreeNode&lt;T&gt;</code> class template, I didn't write its destructor!! So, like what I say above, when node,which is pointed by root of <code>btree</code>, is to be released is there so-called "default destructor"? and is it called here ? And most importantly, is "DELETE" used by the program?</li> </ol> <p>If one of the two question above is no, is it why the problem arise?</p> <p>EDIT: now the problem is shown, but how can I adjust my code to fix this? any one any idea?</p> <p>EDIT: just modify like this:</p> <pre><code>uniTreeNode&lt;date&gt; *nodeptr = new uniTreeNode&lt;date&gt;(d1, NULL, NULL); </code></pre> <p>p.s. if not indirectly using a pointer to refer to our root of the btree(thus using new), new isn't used, and delete shouldn't be used; by this choice, delete_helper of uniTreenode should use this:</p> <pre><code>if(n != root){ delete n; count++; } </code></pre> <p>but this does not solve the problem... the ultimate question is:</p> <pre><code>"can we release object without using delete(because it isn't obtained from newing) in c++?" </code></pre> <p>REPLY:</p> <p>My "release"/"allocated" is actually saying about the memory, without specifying HOW it is done...but it's a big issue anyway</p> <p>You say "you can do that but it is almost always the wrong answer";you mean that I should use DELETE but not directly call the destructor?(actually that doesn't seem proper at all) -->please justify here</p> <p>Btw, for those instance NEWed by me, is it necessary for them to be DELETED by a statement if I want to release them? or they'll also be dealt like those automatic variable instance?(back when out of scope, by compiler) -->please correct the above if needed</p> <p>another Q: isn't there ANY existing statement I can use to do things, like what DELETE does, for those automatic instance? or, I can only call destructor, if I wish?</p>
 

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