hello. Everybody Im new in programming. Still learning. Currently I have a problem when designing a Sparse Matrix class. Class is based on a linked list which records only the non-zero elements. Source file seems to compile fine, but at a run it crashes. Debug reveals a segmentation fault, which is as far as I know connected with inproper memory allocation. However I don't seem to find the problem. This is just a base class which allows to insert non-zero elements and display them. I am using bloodshed Dev C++. Any help would be appreciated. thanks Milenkom.

Code:#include <iostream> using namespace std; class Sparse { private: class Elem { private: int row,column; double*elem; Elem*next; public: Elem(){next=NULL;} Elem(int a,int b,double h); ~Elem(){delete elem;} Elem*& Next(){return next;} double& Value()const{return *elem;} int& Row(){return row;} int& Column(){return column;} }; Elem*first; int rows; int columns; public: Sparse(int,int); ~Sparse(); void Insert(int a,int b,double h); friend ostream& operator<<(ostream&,Sparse&); }; Sparse::Elem::Elem(int a,int b,double h) { elem=new double; *elem=h; next=NULL; row=a; column=b; } Sparse::Sparse(int a,int b):rows(a),columns(b) { } Sparse::~Sparse() { Sparse::Elem*handy=first; Sparse::Elem*prev; while(handy!=NULL) { prev=handy; handy=handy->Next(); delete prev; } } void Sparse::Insert(int a,int b,double h) { Sparse::Elem*prvi=new Sparse::Elem(a,b,h); Sparse::Elem*handy; if(first==NULL) { first=prvi; } else { handy=first; while(handy->Next()!=NULL) { handy=handy->Next(); } handy->Next()=prvi; } } ostream& operator<<(ostream &os,Sparse &s) { for(int j=1;j<=s.columns;j++) { for(int i=1;i<=s.rows;i++) if(s.first->Column()==j && s.first->Row()==i) { cout<<s.first->Value()<<" "; s.first=s.first->Next(); } else cout<<0<<" "; cout<<"\n"; } return os; } int main() { Sparse s1(10,10); s1.Insert(1,1,10); s1.Insert(2,1,20); s1.Insert(3,2,30); cout<<s1; system("PAUSE"); return 0; }