Xstring error !! PLZ HELPPP!!!

this is my code.. but i get error in xstring header file at this part
size_type size() const
{ // return length of sequence
return (this->_Mysize);
}

here's my full code
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;





struct node
{
string title;
string artist;

node* right;
node* left;
};


class song
{
private:
node *root;
node *insertx(string song,string artist,node *xyz)
{
if(song<xyz->title)
{
if(xyz->left==NULL)
{
xyz->left=new node;
xyz->left->left=NULL;
xyz->left->title=song;
xyz->left->artist=artist;
xyz->left->right=NULL;
}
else
{
insertx(song,artist,xyz->left);
}

}
else if(song>xyz->title)
{
if(xyz->right==NULL)
{
xyz->right=new node;
xyz->right->left=NULL;
xyz->right->title=song;
xyz->right->artist=artist;
xyz->right->right=NULL;
}
else
{
insertx(song,artist,xyz->right);
}

}
return xyz;
}
node *searchbytitle(string song,node *xyz)
{
if(song==xyz->title)
{
return xyz;
}
else if(song<xyz->title)
{
if(xyz->left!=NULL)
{
searchbytitle(song,xyz->left);
}
else
{
return NULL;
}
}
else if(song>xyz->title)
if(xyz->right!=NULL)
{
searchbytitle(song,xyz->right);
}
else
{
return NULL;
}

}
void deletesong(string song,node *xyz)
{
node*a;
a=new node;
if(song==xyz->title)
{
xyz->left=a;
xyz->left->left=a->left;
xyz->left->artist=a->artist;
xyz->left->title=a->title;
delete xyz;

}
else if(song<xyz->title)
{
deletesong(song,xyz->left);
}
else if(song>xyz->title)
{
deletesong(song,xyz->right);
}
cout<<"DELETED!!! \n ";

}
void searchbyartist(string artist,node *xyz)
{
node*temp;
temp=new node;
temp=root;
while(temp->left!=NULL)
{
if(artist==temp->artist)
{
cout<<temp->title<<endl;
}
temp=temp->left;
}
while(temp->right!=NULL)
{
if(artist==temp->artist)
{
cout<<temp->title<<endl;

}
temp=temp->right;
}
}
public:
song(){root=NULL;}
node* insert(string song,string artist)
{
node*temp;
temp=new node;
if (root==NULL)
{
root=new node;
root->artist=artist;
root->title=song;
root->left=NULL;
root->right=NULL;
temp=root;
}
else
{
temp= insertx(song,artist,root);
}
cout<<"\n\nSong added to the library \n";
return temp;
}
node* titlesearch(string song)
{
node *temperory;
temperory=new node;
if (song==root->title)
{
return root;
}
else
{
temperory=searchbytitle(song,root);
return temperory;
}
}
void artistsearch(string artist)
{
searchbyartist(artist,root);
}
void deletesongs(string song)
{
deletesong(song,root);
}
void display(node* data)
{
node *datax;
datax=new node;
datax=data;
while(data->left!=NULL)
{
data=data->left;
cout<<data->title<<setw(7)<<data->artist<<endl;
}
while(datax->right!=NULL)
{
datax=datax->right;
cout<<datax->title<<setw(7)<<datax->artist<<endl;
}
}
};

void menu()
{
song x;
node *temp;
temp=new node;
int a=0;
string title="";
string artist="";
cout<<"****WELCOME TO YOUR MUSIC LIBRARY****\n Please Pick One Of Following Options -: \n";
cout<<"1)Add a New Song \n2)Search a Song \n3)Delete a song \n4)Display Your Music Database\n";
cin>>a;
if (a==1)
{
cin.ignore();
cout<<"\n\nPlease Enter New Song's Title \n";
getline(cin,title);


cout<<"\n\nPlease Enter it's Artist's name \n";
getline(cin,artist);
cin.ignore();
temp=x.insert(title,artist);
}
else if (a==2)
{

int c=0;
cout<<"**Enter 1 for searching by song's title \n";
cout<<"**Enter 2 for searching by song's artist \n";
cin>>c;
if(c==1)
{
node*d;
d=new node;
cout<<"Enter Song's title \n";
cin.ignore();
getline(cin,title);
d=x.titlesearch(title);
cout<<d->title<<" "<<d->artist<<endl;
}
else if(c==2)
{
cout<<"Enter Artist Name \n";
cin.ignore();
getline(cin,artist);
x.artistsearch(artist);


}
else
{
cout<<"***ERROR***WRONG CHOICE INPUT***\n";
}
}
else if (a==3)
{
cout<<"Enter song's name \n";
getline(cin,title);
x.deletesongs(title);
cout<<endl;
}
else if(a==4)
{
x.display(temp);
}
int f=0;

cout<<"\n\nPress 1 to Continue Managing Library \n";
cin>>f;
if(f==1)
{
menu();
}
}

int main()
{
menu();
return 0;
}

plzzzzzzz help , as i really need it to work.. thanks

Before posting, please format your code and use code tags. Go Advanced, select the code and click '#'. Your code as posted is just about unreadable.

Have you debugged the code using the debugger? What part of your code is causing the problem?

Also you have memory leaks as you are using new in several places without corresponding deletes. Normally new would be in the class functions with the corresponding deletes in the class destructor.

Code:

---

node*d;
d=new node;
cout<<"Enter Song's title \n";
cin.ignore();
getline(cin,title);
d=x.titlesearch(title);

---

Why assign memory to d for d to be then overwritten? You can't then delete the memory allocated to d as you have lost the memory address so have a memory leak.

As 2kaud said, please format your code. It's very difficult to work with like that. I ran it in the debugger and it very quickly showed me that root was null int your titlesearch function.