program not holding assigned value, sets it to null
Nov 27, 2010 at 7:52pm UTC
Hello, The program compiles, but its not doing what it suppose to. The program creates a tree and connects to the root, but when it exists out, after creating it the root is set back to null, i am not sure why, i am passing the root pointer it self.
1#include <iostream>
using namespace std;
class Tree
{
private :
Tree * left;
int Data;
Tree * right;
public :
Tree(int a);
void setdata(int );
void setleft(Tree *);
void setright(Tree *);
Tree * getleft();
Tree * getright();
int getdata();
void print(Tree *);
void search (Tree *,int );
};
Tree::Tree(int a)
{
Data = a;
left =NULL;
right = NULL;
}
void Tree::setdata(int given)
{
Data = given;
}
void Tree::setleft(Tree * lft_tree)
{
left = lft_tree;
}
void Tree::setright(Tree * rgt_tree)
{
right = rgt_tree;
}
Tree * Tree::getleft()
{
return (left);
}
Tree * Tree::getright()
{
return (right);
}
int Tree::getdata()
{
return (Data);
}
void Tree::print(Tree * root)
{
if (root != NULL)
{
cout<<"in the print" <<endl;
print(root->getleft());
cout<<root->Data<<endl;
print(root->getright());
}
}
void Tree::search(Tree * root,int a)
{
if (root !=NULL)
{
cout<<"in search" <<endl;
if (root->getdata()==a)
{
cout<<root->getdata()<<endl;
cout<<"found" <<endl;
}
else
{
if (a>root->getdata())
{
search(root->getleft(),a);
}
else if (a<root->getdata())
{
search(root->getright(),a);
}
}
}
// cout <<"Not found"<<endl;
}
///**************************************************
class head
{
private :
Tree * big;
public :
head();
void setbig(Tree *);
void newtree(int );
Tree * getbig();
void searchandinsert(Tree *,int );
void print();
};
void head::print()
{
cout<<"in head print" <<endl;
big->print(big);
cout<<"missed" <<endl;
}
head::head()
{
big =NULL;
}
void head::setbig(Tree * give)
{
big = give;
}
Tree * head::getbig()
{
return big;
}
void head::newtree(int x)
{
searchandinsert(big,x);
}
void head::searchandinsert(Tree * root, int x)
{
if (root == NULL)
{
root = new Tree(x);
}
if (x>root->getdata())
{
searchandinsert(root->getleft(),x);
}
if (x<root->getdata())
{
searchandinsert(root->getright(),x);
}
}
/// WHEN PROGRAM EXIT OUT OF HERE THE NEW DATA IS LOST, ROOT IS BACK TO NULL
///****************************************
int main()
{
head root;
root.newtree(5);
root.newtree(8);
root.print();
}
i used DDD debugger to trace it. any one know what's the error here? Thank you in advance
Last edited on Nov 27, 2010 at 7:53pm UTC
Nov 27, 2010 at 8:31pm UTC
That is because you aren't modifying root, you are modifying a copy of it. Pass it by reference or pointer if you need to change the value.
Nov 27, 2010 at 8:49pm UTC
so i would say,
1class head
{
private :
Tree * big;
public :
head();
void setbig(Tree *);
void newtree(int );
Tree * getbig();
void searchandinsert(Tree *&,int );
void print();
};
...
..
void head::newtree(int x)
{
searchandinsert(&big,x);
}
void head::searchandinsert(Tree *& root, int x)
{
if (root == NULL)
{
root = new Tree(x);
}
if (x>root->getdata())
{
searchandinsert(&root->getleft(),x);
}
if (x<root->getdata())
{
searchandinsert(&root->getright(),x);
}
}
Nov 27, 2010 at 9:59pm UTC
Help please.
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