Checkpointer - MQL4

CheckPointer Function

Overview

The CheckPointer function returns the type of an object pointer. It is crucial for validating pointer integrity before accessing the object to prevent critical program termination.

Signature

ENUM_POINTER_TYPE CheckPointer(object* anyobject);

Parameters

anyobject [in]: A pointer to an object.

Return Value

Returns a value from the ENUM_POINTER_TYPE enumeration, indicating the pointer's validity.

Notes

An invalid pointer (e.g., NULL or a pointer to a deleted object) will cause critical program termination if not checked.

Calling CheckPointer before using a pointer is recommended.

A non-zero return value guarantees that the pointer can be safely used for object access.

Related Functions

Alert

Comment

GetPointer

MessageBox

Print

ResetLastError

SetUserError

Sleep

ZeroMemory

Constants

ENUM_POINTER_TYPE (for return values)

Example

//+------------------------------------------------------------------+
//| Deletes list by deleting its elements                            |
//+------------------------------------------------------------------+
void CMyList::Destroy()
  {
//--- service pointer for working in the loop
   CItem* item;
//--- go through loop and try to delete dynamic pointers
   while(CheckPointer(m_items)!=POINTER_INVALID)
     {
      item=m_items;
      m_items=m_items.Next();
      if(CheckPointer(item)==POINTER_DYNAMIC)
        {
         Print("Dynamyc object ",item.Identifier()," to be deleted");
         delete (item);
        }
      else Print("Non-dynamic object ",item.Identifier()," cannot be deleted");
     }
//---
  }

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