c++ - Multiple constructors in a class -

i have class a,b,c,d have member of class x in it. have class called class p.

in class create instance of class p well. in class p need access x instance of , method of (this method available in class b,c,d same method signature , parameters), therefore pass class class p while initializing class p.

so code looks like;

class p; class a{ public:     x x;     p *p;      a(){         x = new x();     };      void setdata(){         p =  new p(this);     } };   class p{ public:     *a;     p(a *_a){         = _a;                     a->x.resetval();     } };  

now need create instances of p in class b,c,d , pass instances of classes p.

to knowledge achieve must either make a,b,c,d child class of new class (class parent) , set constructor of class p accept class parent instance, or must create separate constructors classes a,b,c,d in class p.

class parent {     x x; } class p; class a:: parent{     ...........//code };   class p{ public:     parent *prnt;     impl(parent *prnt){         .........//code     } };  ---------------------- or -------------------------  class p{ public:     *a;     b *a;     c *a;     d *a;      impl(a *_a){         .............//code     }      impl(b *_b){         .............//code     }      impl(c *_c){         .............//code     }      .............//code }; 

i not want change class a,b,c,d because complicated classes not written me. there way achieve other 2 above methods?

any appreciated. thanks.

if need access x instance in each of classes, can pass pointer x instance constructor of p.

class p { public:     x* x;     p(x* _x) {         x = _x;         // code     } };  class a{ public:     x x;     p *p;      a(){         x = new x();     };      void setdata(){         p = new p(x);     } };