I want to pass pointer object to function by reference. I don't know If I am doing correct as It is not working as per below code. Please help me.
class Base
{
public:
int x;
void print()// function prints x value
{
cout<<x;
}
void call_print(Base **base) //function call print function
{
base->print();
}
};
int main()
{
Base *b = new Base; // creating pointer object
b->call_print(&b); // passing pointer by reference
return 0;
}
You're passing the object by "reference" in the sense that you still have access to the original object through the parameter, but note that base in call_print() is a pointer to the object being passed in, not the actual object. You still have to dereference the pointer if you want access to the object passed in:
(*base)->print();
C++ introduced actual references that are syntactic sugar upon what you have to do with pointers/double-pointers. For example:
void call_print(Base*& base)
{ base->print(); }
b->call_print(b);
Also, the use of a double pointer or reference seems unnecessary since you don't need to modify the pointer in any way. Why not just take in the pointer itself?
void call_print(Base* base)
{ base->print(); }
b->call_print(b);
And lastly, you don't need to pass b in as an argument to its own method. A pointer to the Base object is accessible through this:
void call_print()
{
print(); /* or this->print() */
}
b->call_print();
a simple note: don't use naked pointers, take advantage of C++11 facilities: std::unique_ptr and std::shared_ptr are even better, for resource management sake, and you can write something like this:
std::unique_ptr<Base> base_ptr(new Base());
base_ptr->call_print();
//no delete, unique_ptr deletes itself automatically
and for Base class, you have to write:
void call_print() //function call print function
{
this->print();
}
because you don't need to pass to the same object, the reference to itself.
#include <iostream>
using namespace std;
class Base
{
public:
int x;
void print()
{
cout<<x<<endl;
}
};
class Base2
{
public:
void change_value(Base *&base)
{
base->x = 5;
}
};
int main()
{
Base *b = new Base;
Base2 b2;
b2.change_value(b);
b->print();
delete b;
return 0;
}
x if you pass a non-pointer Base by reference! (in other words, you don't need pointers at all, just C++ references)
base->printwon't work withBase **3) why even usenew(and you don'tdeleteanyway).call_printdeclaration:void call_print(Base *base). Also callb->call_print(b)inmainfunction.