#pragma once

class MyClass2;

class MyClass1                  
{
public:
    explicit MyClass1(int val) : a(val) {}
    MyClass1(int val, MyClass2& mc);
    int getA() const { return a; }
    void setB(const MyClass2& val)

private:
    int a;
    int b;
}

#include "MyClass1.h"
#include "MyClass2.h"

MyClass1::MyClass1(int val, MyClass2& mc)
{
    a = val;
    b = mc.getB();
    mc.setA(*this);
}

void MyClass1::setB(const MyClass2& val)
{
    b = val.getB();
}

#pragma once

class MyClass1;

class MyClass2
{
public:
    explicit MyClass2(int val) : b(val) {}
    int getB() const { return b; }
    void setA(const MyClass1& val);

private;
    int a;                  
    int b;
}

#include "MyClass2.h"
#include "MyClass1.h"

void MyClass2::setA(const MyClass1& val)
{
    a = val.getA();
}

#include "MyClass1.h"
#include "MyClass2.h"

int main()
{
    auto mc1 = MyClass1(228);
    auto mc2 = MyClass2(1488);
    mc1.setB(mc2);
    mc2.setA(mc1);
                         
    auto mc3 = MyClass2(1488);
    auto mc4 = MyClass1(228, mc3);
    return 0;
}

#include <iostream>

using namespace std;

class MyClass1
{
public:
     int a;
     int b;
};

class MyClass2
{
public:
     int a;
     int b;
};

int main()
{
     MyClass1 A;
         A.a = 5;
         A.b = 7;
     MyClass2 B;
         B.a = 12;
         B.b = 17;
     cout << A.a + A.b + B.a + B.b << endl;
     return 0;
}

struct partic
{
int life;
float x;
float y;
float dx,dy;
int fade;
};

vector <partic> partics;

for(int i=0;i<maxcount;i++)
     {
     partics.push_back(partic());
     inipartic(i);
     }

void inipartic(int idx)
{
   partics[idx].life=rand()%(lifemax-lifemin)+lifemin; // тут, например.
....
}

for(int i=0;i<maxcount;i++)  
      {  
      partic p;
      partics.push_back(p);  
      inipartic();  
      }

void inipartic()  
{  
    partics[ partics.count() - 1 ].life=rand()%(lifemax-lifemin)+lifemin; // тут, например.  
....  
}  

partics[idx].x=rand()%(rectangle.w)+rectangle.x;
   partics[idx].y=rand()%(rectangle.h)+rectangle.y;
   partics[idx].dx=rand()%(int)(maxspeedX-minspeedX)+minspeedX;
   partics[idx].dy=rand()%(int)(maxspeedY-minspeedY)+minspeedY;

min + (rand() % (int)(max - min + 1))