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CTree

CTree is a class of the binary tree of the instances of CTreeNode class and its descendants.

Description

CTree class provides the possibility to work with the binary tree of CTreeNode class instances and its descendants. Options of adding/inserting/deleting of tree elements and search in the tree are implemented in the class. Besides that, methods of working with a file are implemented.

Note that mechanism of dynamic memory management is not implemented in class CTree (unlike classes CList and CArrayObj). All tree nodes are deleted with memory deallocation.

Declaration

   class CTree : public CTreeNode

Title

   #include <Arrays\Tree.mqh>

Class Methods by Groups

Attributes

 

Root

Gets the root node of the tree

Creation of a new element

 

CreateElement

Creates a new instance of the node

Filling

 

Insert

Adds a node to a tree

Deletion

 

Detach

Detaches a specified node from a tree

Delete

Deletes a specified node from a tree

Clear

Deletes all nodes of a tree

Search

 

Find

Searches for a node in a tree by sample

Input/output

 

virtual Save

Saves all the tree data to a file

virtual Load

Downloads tree data from a file

virtual Type

Gets identifier of the tree type

Trees of CTreeNode class descendants — descendants of class CTree - have practical application.

Descendant of CTree class should have a predefined method CreateElement that creates a new instance of the CTreeNode descendant class.

Let's consider an example of the CTree descendant class.

//+------------------------------------------------------------------+
//|                                                       MyTree.mq5 |
//|                        Copyright 2010, MetaQuotes Software Corp. |
//|                                       http://www.metaquotes.net/ |
//+------------------------------------------------------------------+
#property copyright "2010, MetaQuotes Software Corp."
#property link      "https://www.mql5.com"
//---
#include <Arrays\Tree.mqh>
#include "MyTreeNode.mqh"
//---
input int extCountedNodes = 100;
//+------------------------------------------------------------------+
//| Describe class CMyTree derived from CTree.                       |
//+------------------------------------------------------------------+
//| Class CMyTree.                                                   |
//| Purpose: Construction and navigation of a binary search tree.    |
//+------------------------------------------------------------------+
class CMyTree : public CTree
  {
public:
   //--- methods of searching in the tree by custom data
   CMyTreeNode*        FindByLong(long find_long);
   //--- method of creation of the tree element
   virtual CTreeNode *CreateElement();
  };
//---
CMyTree MyTree;
//+------------------------------------------------------------------+
//| Creation of a new tree node.                                     |
//| INPUT:  none.                                                    |
//| OUTPUT: pointer to the new tree node if OK, or NULL.             |
//| REMARK: none.                                                    |
//+------------------------------------------------------------------+
CTreeNode *CMyTree::CreateElement()
  {
   CMyTreeNode *node=new CMyTreeNode;
//---
   return(node);
  }
//+------------------------------------------------------------------+
//| Search of element in a list by value m_long.                     |
//| INPUT:  find_long - searched value.                              |
//| OUTPUT: pointer of a found list element, or NULL.                |
//| REMARK: none.                                                    |
//+------------------------------------------------------------------+
CMyTreeNode* CMyTree::FindByLong(long find_long)
  {
   CMyTreeNode *res=NULL;
   CMyTreeNode *node;
//--- create a tree node to pass the search parameter
   node=new CMyTreeNode;
   if(node==NULLreturn(NULL);
   node.SetLong(find_long);
//---
   res=Find(node);
   delete node;
//---
   return(res);
  }
//+------------------------------------------------------------------+
//| script "testing of class CMyTree"                                |
//+------------------------------------------------------------------+
//---  array for string initialization
string str_array[11]={"p","oo","iii","uuuu","yyyyy","ttttt","rrrr","eee","ww","q","999"};
//---
int OnStart() export
  {
   int          i;
   uint         pos;
   int          beg_time,end_time;
   CMyTreeNode *node; //--- temporary pointer to the sample of class CMyTreeNode 
//---  
   printf("Start test %s.",__FILE__);
//--- Fill out MyTree with instances of class MyTreeNode in the amount of extCountedNodes.
   beg_time=GetTickCount();
   for(i=0;i<extCountedNodes;i++)
     {
      node=MyTree.CreateElement();
      if(node==NULL)
        {
         //--- emergency exit
         printf("%s (%4d): create error",__FILE__,__LINE__);
         return(__LINE__);
        }
      NodeSetData(node,i);
      node.SetLong(i);
      MyTree.Insert(node);
     }
   end_time=GetTickCount();
   printf("Filling time of MyTree is %d ms.",end_time-beg_time);
//--- Create a temporary tree TmpMyTree.
   CMyTree TmpMyTree;
//--- Detach 50% of tree elements (all even)
//--- and add them to the temporary tree TmpMyTree.
   beg_time=GetTickCount();
   for(i=0;i<extCountedNodes;i+=2)
     {
      node=MyTree.FindByLong(i);
      if(node!=NULL)
         if(MyTree.Detach(node)) TmpMyTree.Insert(node);
     }
   end_time=GetTickCount();
   printf("Deletion time of %d elements from MyTree is %d ms.",extCountedNodes/2,end_time-beg_time);
//--- Return the detached
   node=TmpMyTree.Root();
   while(node!=NULL)
     {
      if(TmpMyTree.Detach(node)) MyTree.Insert(node);
      node=TmpMyTree.Root();
     }
//--- Check work of method Save(int file_handle);
   int file_handle;
   file_handle=FileOpen("MyTree.bin",FILE_WRITE|FILE_BIN|FILE_ANSI);
   if(file_handle>=0)
     {
      if(!MyTree.Save(file_handle))
        {
         //--- error writing to a file
         //--- emergency exit
         printf("%s: Error %d in %d!",__FILE__,GetLastError(),__LINE__);
         //--- close file before leaving!!!
         FileClose(file_handle);
         return(__LINE__);
        }
      FileClose(file_handle);
     }
//--- Check work of method Load(int file_handle);
   file_handle=FileOpen("MyTree.bin",FILE_READ|FILE_BIN|FILE_ANSI);
   if(file_handle>=0)
     {
      if(!TmpMyTree.Load(file_handle))
        {
         //--- error reading from file
         //--- emergency exit
         printf("%s: Error %d in %d!",__FILE__,GetLastError(),__LINE__);
         //--- close file before leaving!!!
         FileClose(file_handle);
         return(__LINE__);
        }
      FileClose(file_handle);
     }
//---
   MyTree.Clear();
   TmpMyTree.Clear();
//---
   printf("End test %s. OK!",__FILE__);
//---
   return(0);
  }
//+------------------------------------------------------------------+
//| Function to output node contents to journal                      | 
//+------------------------------------------------------------------+
void NodeToLog(CMyTreeNode *node)
  {
   printf("   %I64d,%f,'%s','%s'",
               node.GetLong(),node.GetDouble(),
               node.GetString(),TimeToString(node.GetDateTime()));
  }
//+------------------------------------------------------------------+
//| Function to populate node with random values                     | 
//+------------------------------------------------------------------+
void NodeSetData(CMyTreeNode *node,int mode)
  {
   if(mode%2==0)
     {
      node.SetLong(mode*MathRand());
      node.SetDouble(MathPow(2.02,mode)*MathRand());
     }
   else
     {
      node.SetLong(mode*(long)(-1)*MathRand());
      node.SetDouble(-MathPow(2.02,mode)*MathRand());
     }
   node.SetString(str_array[mode%10]);
   node.SetDateTime(10000*mode);
  }

 


Updated: 2016.03.23