[gab00n]

I have this program that has to accept a string from the user, then a second one and a place to insert the string into the first string. Both strings will be linked lists and i have to insert string 2 into string one where the user asked. The problem i am having is in the function insertafter. It was a worksheet that i had to complete the code, all i was given for the insertafter function was three pointers. I have been looking at it for a while and can't seem to figure out what is causing the problem. It is probably something stupid but i just can't see it. Any help will be most appreciated, thanks.

#include <iostream>
using namespace std;

struct StringRec
{
       char theCh;
       StringRec* nextCh;
};
typedef StringRec* StrPtr;

class String
{
       public:
               String();
               ~String();
               void SetString();
               void OutputString();
               int GetLength()const;
       protected:
               StrPtr head;
               int strLength;
};

class StringModifier: public String
{
       public:
               StringModifier();
               ~StringModifier();
               void InsertAfter(StringModifier& subStr, int num);
};

int main()
{

       StringModifier str1, str2;
       int num = 0;

       str1.SetString();
       cout<<endl<<"The string before modification: ";
       str1.OutputString();
       cout<<endl;

       str2.SetString();
       cout<<"\nEnter place to insert string: ";
       cin>>num;
       cout<<endl;
       str2.OutputString();
       cout<<endl;

       str1.InsertAfter(str2, num);
       cout<<endl;
       str1.OutputString();

       cout<<endl;

       return 0;
}

String::String(): head(NULL), strLength(0)
{

}

String::~String()
{
       StrPtr p;
       p = head;
       while(head != NULL)
       {
            delete p;
            p = NULL;
            head = head->nextCh;
            p = head;
       }
       delete p;
       p = NULL;
       head = NULL;
}

void String::SetString()
{
       StrPtr p, last;
       char tempCh;
       last = head;
       cout<<"\nEnter a string: ";
       cin.get(tempCh);
       while(tempCh != '\n')
       {
            p = new StringRec;
            p->theCh = tempCh;
            p->nextCh = NULL;
            strLength++;
            if(head == NULL)
            {
                head = p;
                last = p;
            }
            else
            {
                last->nextCh = p;
                last = p;
            }
            cin.get(tempCh);
       }

}

void String::OutputString()
{
       StrPtr p;
       p = head;
       while(p != NULL)
       {
               cout<<p->theCh;
               p = p->nextCh;
       }
       delete p;
}

int String::GetLength()const
{
       return strLength;
}

StringModifier::StringModifier():String()
{

}

StringModifier::~StringModifier()
{
       StrPtr p;
       p = head;
       while(head != NULL)
       {
           delete p;
           p = NULL;
           head = head->nextCh;
           p = head;
       }
       delete p;
       p = NULL;
}

void StringModifier::InsertAfter(StringModifier& subStr, int num)
{
       StrPtr p, q, r;
       p =  head;
       q = subStr.head;

       for(int i = 0; i<num; ++i)
       {
           p = p->nextCh;
       }
       r = p;
       r = r->nextCh;
       p->nextCh = q;

       while(q != NULL)
       {
           q = q->nextCh;
       }
       q->nextCh = r;
}