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CArrayObj

CArrayObj class is a class of dynamic array of pointers to instances of CObject and its derived classes.

Description

Class CArrayObj provides the ability to work with a dynamic array of pointers to instances of CObject and its derived classes. This allows working both with multidimensional dynamic arrays of primitive data types and with data structures that have more complex organization of data.

The class allows adding/inserting/deleting array elements, performing an array sorting, and searching in a sorted array. In addition, methods of working with files have been implemented.

There are certain subtleties of the class CArrayObj.

Declaration

   class CArrayObj : public CArray

Title

   #include <Arrays\ArrayObj.mqh>

Class Methods by Groups

Attributes

 

FreeMode

Gets the flag of memory management

FreeMode

Sets the flag of memory management

Memory control

 

Reserve

Allocates memory to increase the size of the array

Resize

Sets a new (smaller) size of the array

Shutdown

Clears the array with full deallocation of its memory (but not its elements).

Creating a new element

 

virtual CreateElement

Creates a new array element in the specified position

Add methods

 

Add

Adds an element to the end of the array

AddArray

Adds an element to the end of the array

Insert

Inserts an element to the specified position in the array

InsertArray

Inserts to an array elements from another array from the specified position

AssignArray

Copies the elements of one array to another

Update methods

 

Update

Changes the element at the specified position array

Shift

Moves an item from a given position in the array to the specified offset

Delete methods

 

Detach

Gets the element from the specified position and removes it from the array

Delete

Removes the element from the specified array position

DeleteRange

Deletes a group of elements from the specified array position

Clear

Removes all elements of the array without the release of the array memory

Access methods

 

At

Gets the element from the specified array position

Compare methods

 

CompareArray

Compares the array with another one

Sorted array operations

 

InsertSort

Inserts an element in a sorted array

Search

Searches for an element equal to the sample in the sorted array

SearchGreat

Searches for an element with a value exceeding the value of the sample in the sorted array

SearchLess

Searches for an element with a value less than the value of the sample in the sorted array

SearchGreatOrEqual

Searches for an element with a value greater than or equal to the value of the sample in the sorted array

SearchLessOrEqual

Searches for an element with a value less than or equal to the value of the sample in the sorted array

SearchFirst

Searches for the first element equal to the sample in the sorted array

SearchLast

Searches for the last element equal to the sample in the sorted array

Input/output

 

Save

Saves data array in the file

Load

Loads data array from the file

Type

Gets the type identifier of the array

Derived classes:

Arrays of the CObject class have practical application (including all classes of the Standard Library).

For example, consider the options for two-dimensional array:

#include <Arrays\ArrayDouble.mqh>
#include <Arrays\ArrayObj.mqh>
//---
void OnStart()
  {
   int i,j;
   int first_size=10;
   int second_size=100;
//--- create array
   CArrayObj    *array=new CArrayObj;
   CArrayDouble *sub_array;
//---
   if(array==NULL)
     {
      printf("Object create error");
      return;
     }
//--- create subarrays
   for(i=0;i<first_size;i++)
     {
      sub_array=new CArrayDouble;
      if(sub_array==NULL)
        {
         delete array;
         printf("Object create error");
         return;
        }
      //--- fill array
      for(j=0;j<second_size;j++)
        {
         sub_array.Add(i*j);
        }
      array.Add(sub_array);
     }
//--- create array OK
   for(i=0;i<first_size;i++)
     {
      sub_array=array.At(i);
      for(j=0;j<second_size;j++)
        {
         double element=sub_array.At(j);
         //--- use array element
        }
     }
   delete array;
  }

Subtleties

The class has a mechanism to control dynamic memory, so be careful when working with elements of the array.

Mechanism of memory management can be switched on/off using the method FreeMode (bool). By default, the mechanism is enabled.

Accordingly, there are two options for dealing with the CArrayObj class:

1. Mechanism of memory management is enabled. (default)

In this case, CArrayObj takes responsibility for releasing the memory used for the elements after their removal from the array. A custom program should not release the array elements.

Example:

   int i;
//--- create an array
   CArrayObj *array=new CArrayObj;
//--- fill array elements
   for(i=0;i<10;i++) array.Add(new CObject);
//--- do something
   for(i=0;i<array.Total();i++)
     {
      CObject *object=array.At(i);
      //--- actions performed with the element
      . . .
     }
//--- remove the array with the elements
   delete array;

2. Mechanism of memory management is disabled.

In this case, CArrayObj is not responsible for deallocating of the elements' memory after their removal from the array. Besides, the user program must deallocate the array elements.

Example:

   int i;
//--- create an array
   CArrayObj *array=new CArrayObj;
//--- disable the mechanism of memory management
   array.FreeMode(false);
//--- fill array with elements
   for(i=0;i<10;i++) array.Add(new CObject);
//--- do something
   for(i=0;i<array.Total();i++)
     {
      CObject *object=array.At(i);
      //--- actions performed with the element
      . . .
     }
//--- remove array elements
   while(array.Total()) delete array.Detach();
//--- remove empty array
   delete array;

 


Updated: 2016.03.17