C++ Pointers to Structure

A pointer variable can be created not only for built-in types like (int, float, double etc.) but they can also be created for user defined types like structure.

If you do not know what pointers are, visit C++ pointers.

Example: Pointers to Structure

#include <iostream>
using namespace std;

struct Distance {
    int feet;
    float inch;
};

int main() {
    Distance d;
    Distance* ptr = &d;
    
    cout << "Enter feet: ";
    cin >> (*ptr).feet;
    cout << "Enter inch: ";
    cin >> (*ptr).inch;
 
    cout << "Displaying information." << endl;
    cout << "Distance = " << (*ptr).feet << " feet " << (*ptr).inch << " inches";

    return 0;
}

Output

Enter feet: 4
Enter inch: 3.5
Displaying information.
Distance = 4 feet 3.5 inches

Here, the address of variable d is stored in the pointer variable ptr, which means ptr is pointing to variable d.

Distance* ptr = &d;

Then, the member function of variable d is accessed using the pointer.

cin >> (*ptr).feet;

Arrow (->) Operator

We can use the arrow (->) operator to access member variables and member functions of a structure variable through a pointer.

Accessing Member Variable Using Arrow (->) Operator Example

#include <iostream>
using namespace std;

struct Distance {
	int feet;
	float inch;
};

int main() {
	Distance d;

	Distance* ptr = &d;
    
	cout << "Enter feet: ";
	cin >> ptr->feet;
	cout << "Enter inch: ";
	cin >> ptr->inch;
 
	cout << "Displaying information." << endl;
	cout << "Distance = " << ptr->feet << " feet " << ptr->inch << " inches";

	return 0;
}

Output

Enter feet: 4
Enter inch: 3.5
Displaying information.
Distance = 4 feet 3.5 inches

Here, the address of variable d is stored in the pointer variable ptr which means ptr is pointing to variable d.

Distance* ptr = &d;

Then, the member variable of variable d is accessed using the pointer.

cin >> ptr->feet;

Note: (*ptr).inch and ptr->inch are equivalent.

Accessing Member Function Using Arrow (->) Operator Example

#include <iostream>
using namespace std;

struct Distance {
    int feet;
    float inch;
    
    void print_distance() {
    	cout << "Displaying Information." << endl;
    	cout << "Distance = " << feet << " feet " << inch << " inches";
    }
};

int main() {
    Distance d;

    Distance* ptr = &d;
    
    cout << "Enter feet: ";
    cin >> ptr->feet;
    cout << "Enter inch: ";
    cin >> ptr->inch;
    
    ptr->print_distance();

    return 0;
}

Output:

Enter feet: 4
Enter inch: 3.5
Displaying Information.
Distance = 4 feet 3.5 inches

Here, the member function of variable d is accessed using the pointer.

ptr->print_distance();