C++ Pointers to Structures

Pointers are a powerful concept in C++ that allow you to manipulate memory locations directly. In C++, you can use pointers with structures to access and modify structure data efficiently.

Declaring a Pointer to a Structure

To declare a pointer to a structure, use the structure name followed by an asterisk * and the pointer name.

Example:

1struct Person
2{
3    string name;
4    string address;
5    int age;
6};
7
8Person *personPointer;

In this example, we have declared a pointer to a structure named personPointer of type Person.

Accessing Structure Members Using a Pointer

To access the members of a structure using a pointer, use the pointer name followed by the arrow -> operator and the member name.

Example:

1#include <iostream>
2#include <string>
3using namespace std;
4 
5struct Person
6{
7    string name;
8    string address;
9    int age;
10};
11 
12int main()
13{
14    Person person1;
15    person1.name = "William Max";
16    person1.address = "123 Main Street";
17    person1.age = 30;
18 
19    Person *personPointer;
20    personPointer = &person1;
21 
22    cout << "Name: " << personPointer->name << endl;
23    cout << "Address: " << personPointer->address << endl;
24    cout << "Age: " << personPointer->age << endl;
25 
26    return 0;
27}

Output:

1Name: William Max
2Address: 123 Main Street
3Age: 30

In this example, we have defined a structure variable named person1 and assigned values to its members name, address, and age. We then declared a pointer to a structure named personPointer and assigned the address of person1 to it using the address-of operator &. Finally, we access the members of the structure using the arrow -> operator and print their values to the console.

Using a Pointer to Modify Structure Members

To modify the members of a structure using a pointer, use the pointer name followed by the arrow -> operator and the member name.

Example:

1#include <iostream>
2#include <string>
3using namespace std;
4 
5struct Person
6{
7    string name;
8    string address;
9    int age;
10};
11 
12int main()
13{
14    Person person1;
15    person1.name = "William Max";
16    person1.address = "123 Main Street";
17    person1.age = 30;
18 
19    Person *personPointer;
20    personPointer = &person1;
21 
22    cout << "Name: " << personPointer->name << endl;
23    cout << "Address: " << personPointer->address << endl;
24    cout << "Age: " << personPointer->age << endl;
25 
26    personPointer->name = "Jane Max";
27    personPointer->address = "456 Main Street";
28    personPointer->age = 31;
29 
30    cout << "Name: " << personPointer->name << endl;
31    cout << "Address: " << personPointer->address << endl;
32    cout << "Age: " << personPointer->age << endl;
33    
34    return 0;
35}

Output:

1Name: William Max
2Address: 123 Main Street
3Age: 30
4Name: Jane Max
5Address: 456 Main Street
6Age: 31

In this example, we have modified the members of the structure using the pointer personPointer and the arrow -> operator. After modifying the values, we print the new values to the console and verify that they have been changed.