dot (.) operator in C++

The C++ dot (.) operator is used for direct member selection via the name of variables of type class, struct, and union. It is also known as the direct member access operator. It is a binary operator that helps us to extract the value or the function associated with the particular object, structure or union.

Syntax:

variable_name.member;

• variable_name: Its an instance of a class, structure or union.
• member: member variables or member functions associated with the created object, structure or union.

Example:

C++

// C++ Program to demonstrate the use of dot operator
#include <iostream>
using namespace std;

class base {
public:
    int var1;

    base(int x) { var1 = x; }

    void getValue()
    {
        cout << "Member Function Called" << endl;
    }
};

// driver code
int main()
{
    // creating new object
    base b(222);
    // calling member function using dot(.) operator
    b.getValue();
    // getting member variable
    cout << "Member Variable Value: " << b.var1;
    return 0;
}

Output

Member Function Called
Member Variable Value: 222

Frequently Asked Questions about dot (.) Operators in C++

Is dot (.) actually an Operator?

Yes, dot (.) is actually an operator in C/C++ which is used for direct member selection via object name. It has the highest precedence in Operator Precedence and Associativity Chart after the Brackets.

Is there any other Operator like the dot(.) operator?

Yes. There is another such operator (->). It is called an “Indirect member selection” operator and its precedence is same as that of the dot (.) operator. It is used to access the members indirectly with the help of pointers.

Example:

C++

// C++ Function
// tO demonstrate
// Indirect member selection operator
void addXtoList(Node* node, int x)
{
    // Node is a class

    while (node != NULL) {
        node->data = node->data + x;
        node = node->next;
    }
}

Can the dot (.) operator be overloaded?

No, the dot (.) operator cannot be overloaded in C++. Doing so will cause an error.

Example:

C++

// C++ program
// illustrate Overloading
// .(dot) operator

#include <iostream>;
using namespace std;

class cantover {
public:
    void fun();
};

// assume that you can overload . operator
// Class X below overloads the . operator
class X {

    cantover* p;

    // Overloading the . operator
    cantover& operator.() { return *p; }

    void fun();
};

void g(X& x)
{

    // Now trying to access the fun() method
    // using the . operator
    // But this will throw an error
    // as we have overloaded the . operator above
    // Hence compiler won't allow doing so
    x.fun();
}

Output:

prog.cpp:11:20: error: expected type-specifier before '.' token
  cantover& operator.() 
                    ^
prog.cpp:11:12: error: expected ';' at end of member declaration
  cantover& operator.() 
            ^
prog.cpp:11:20: error: expected unqualified-id before '.' token
  cantover& operator.() 
                    ^
prog.cpp: In function 'void g(X&)':
prog.cpp:15:7: error: 'void X::fun()' is private
  void fun(); 
       ^
prog.cpp:19:8: error: within this context
  x.fun(); // X::fun or cantover::fun or error? 
        ^