MQL4 struct containing adress to other structs - struct

Question

I need to code something like that but I don't know the right syntax in the second structure to have fields containing address to structure of first type.
struct ConditionSet
{
int CondsNbr; // Number of cond-s in the set
bool TabConds [MaxConditions];
string TabCondsLabel [MaxConditions];
int CandleNum [MaxConditions];
bool ExitCondition;
int int1, int2, int3, int4, int5; // user integers
double d1, d2, d3,d4, d5; // user doubles
};
struct Transaction
{
string Strategie_name;
string Symbol;
bool BuyReady;
bool SellReady;
bool BuyRunning;
bool SellRunning;
ConditionSet & conditionsAchat; // HERE, THIS IS NOT A CORRECT SYNTAX
ConditionSet & conditionsVente; // HERE, THIS IS NOT A CORRECT SYNTAX
int ticketAchat;
int ticketVente;
};

Answer 1

If a structure contains variables of the string type and/or object of a dynamic array, the compiler assigns an implicit constructor to such a structure. This constructor resets all the structure members of string type and correctly initializes objects of the dynamic array.
Object Pointers
In MQL4, there is a possibility to dynamically create objects of complex type. This is done by the new operator, which returns a descriptor of the created object. Descriptor is 8 bytes large. Syntactically, object descriptors in MQL4 are similar to pointers in C++.
MyObject* hobject= new MyObject();
In contrast to C++, the hobject variable from example above is not a pointer to memory, but rather an object descriptor. Furthermore, in MQL5 all objects in function parameters must be passed by reference.
//+------------------------------------------------------------------+
//| Objects are always passed by reference |
//+------------------------------------------------------------------+
void PrintObject(Foo &object)
{
Print(__FUNCTION__,": ",object.m_id," Object name=",object.m_name);
}
//+------------------------------------------------------------------+
//| Passing an array of objects |
//+------------------------------------------------------------------+
void PrintObjectsArray(Foo &objects[])
{
int size=ArraySize(objects);
for(int i=0;i<size;i++)
{
PrintObject(objects[i]);
}
}
//+------------------------------------------------------------------+
//| Passing an array of pointers to object |
//+------------------------------------------------------------------+
void PrintPointersArray(Foo* &objects[])
{
int size=ArraySize(objects);
for(int i=0;i<size;i++)
{
PrintObject(objects[i]);
}
}
//+------------------------------------------------------------------+
class Foo
{
public:
string m_name;
int m_id;
static int s_counter;
//--- constructors and desctructors
Foo(void){Setup("noname");};
Foo(string name){Setup(name);};
~Foo(void){};
//--- initializes object of type Foo
void Setup(string name)
{
m_name=name;
s_counter++;
m_id=s_counter;
}
};
//+------------------------------------------------------------------+
int Foo::s_counter=0;
//+------------------------------------------------------------------+
//| Script program start function |
//+------------------------------------------------------------------+
void OnStart()
{
//--- declare an object as variable with its automatic creation
Foo foo1;
//--- variant of passing an object by reference
PrintObject(foo1);
//--- declare a pointer to an object and create it using the 'new' operator
Foo *foo2=new Foo("foo2");
//--- variant of passing a pointer to an object by reference
PrintObject(foo2); // pointer to an object is converted automatically by compiler
//--- declare an array of objects of type Foo
Foo foo_objects[5];
//--- variant of passing an array of objects
PrintObjectsArray(foo_objects); // separate function for passing an array of objects
//--- declare an array of pointers to objects of type Foo
Foo *foo_pointers[5];
for(int i=0;i<5;i++)
{
foo_pointers[i]=new Foo("foo_pointer");
}
//--- variant of passing an array of pointers
PrintPointersArray(foo_pointers); // separate function for passing an array of pointers
//--- it is obligatory to delete objects created as pointers before termination
delete(foo2);
//--- delete array of pointers
int size=ArraySize(foo_pointers);
for(int i=0;i<5;i++)
delete(foo_pointers[i]);
//---
}
//+------------------------------------------------------------------+
Keyword this
A variable of class type (object) can be passed both by reference and by pointer. As well as reference, the pointer allows having access to an object. After the object pointer is declared, the new operator should be applied to it to create and initialize it.
The reserved word this is intended for obtaining the reference of the object to itself, which is available inside class or structure methods. this always references to the object, in the method of which it is used, and the expression GetPointer(this) gives the pointer of the object, whose member is the function, in which call of GetPointer() is performed. In MQL4 functions can't return objects, but they can return the object pointer.

Answer 2

Thank you for replying.
After moving the Foo class to the top of the source, and adding the strict property, I could compile your source.
I don't understand the line
int Foo::s_counter=0;
What it does ?
I'm thinking how classes could resolve my problem but it's not easy.
Janfi