stack list debug assertion failed c++ -

when try run code, show me debug assertion failed .any 1 can me, doing stack list,in header file, create struct has 3 variable, string * s, int numoflength, stackframe * next

     void stack::push(string& s)         {              stackframeptr temp_ptr;             temp_ptr=new stackframe;             temp_ptr->str=new string[s.size()];             (temp_ptr->str)[0]=s;             cout<<temp_ptr->str[0]<<endl;             temp_ptr->num_char=sizeofstring(s);             if(empty())             {                 top=temp_ptr;                 temp_ptr->next=null;             }             else             {                 temp_ptr->next=top;                 top=temp_ptr;             }         }  code push think maybe errors because of function. string stack::pop() {     if(empty())         exit(1);     string * name;     stackframeptr temp;     temp=top;     name=top->str;     top=top->next;     delete temp;     return *name; }  #include <iostream> #include "stack.h" #include <string> using namespace std; int main() {     string str1="to";     string str2="hi";     string str3="food";     string str4="ba";     string str5="ti";     string str6="zhilong";     stack s;     s.push(str1);     s.push(str2);     s.push(str3);     s.push(str4);     s.push(str5);     s.push(str6);     cout<<s;     system("pause");     return 0; } 

when try run main function give me debug failure, can me?

class stack { public:     stack();     //default constructor used create empty stack object.      ~stack();     //destructor stack objects.      void push(string& str);      string pop();      bool empty();     //checks see if stack empty.  returns true if empty, else returns false.     //stack remains unchanged after function call.       friend ostream &operator<<(ostream & out_stream, stack & mystack);      friend istream &operator>>(istream & in_stream, stack & mystack);  private:     stackframeptr top; // points top of stack;  }; ostream &operator<<(ostream & outs, stack & sta) {     if(sta.empty())         exit(1);     else     {         stackframeptr read;         read=sta.top;         while(read!=null)         {             outs<<"string = "<<read->str[0]<<endl;             outs<<" number of charcter is" <<read->num_char;             read=read->next;             outs<<endl<<endl;         }     }     return outs; } 

in push allocate array of string, , assign str member of stack. in pop copy str name, delete temp (i'm assuming) delete array name pointing in to. lastly dereference dangling pointer , access memory has been freed.

to fix this, declare name string, rather pointer string, set name=*top->str or name=top->str[0].