Pointers to Structures in C++

February 3, 2023

C++ language – Pointers to Structures

In C++, a pointer is a variable that stores the memory address of another variable. A pointers to structures in C++ is a user-defined data type that consists of a collection of variables of different data types.You can use pointers to structures in C++ to reference the memory location of a structure variable.

Pointers to Structures in C++ img

Pointer to Structures in C++

Here is an example of how you might declare a structure and a pointer to it in C++:

struct Student {
char name[30];
int age;
float grade;
};

struct Student *ptr;

To access the members of a structure using a pointer, you can use the “arrow” operator (->). For example:

ptr->name;   // accesses the "name" member of the structure pointed to by "ptr"
ptr->age;    // accesses the "age" member of the structure pointed to by "ptr"
ptr->grade;  // accesses the "grade" member of the structure pointed to by "ptr"

You can also use the “dot” operator (.) to access the members of a structure, but this requires that you have the actual structure variable rather than just a pointer to it. For example:

struct Student s;

s.name;   // accesses the "name" member of the structure "s"
s.age;    // accesses the "age" member of the structure "s"
s.grade;  // accesses the "grade" member of the structure "s"

Pointers to structures can be useful when you want to pass a structure to a function by reference (i.e., modify the structure within the function) or when you want to create an array of structures and access the elements using pointers.

Function in C++

Static Members in C++

virtual in C++

Pointers in C++

References in C++

Pass a pointer to the structure:

Run 
#include <iostream>
using namespace std;

struct Employee {
  string name;
  int age;
  double salary;
};

int main() {
  
  // create a Employee structure variable 
  Employee e;
  
  // accessing the members of Employee structure
  e.name = "John";
  e.age = 30;
  e.salary = 50000.0;

  // create a pointer to the Employee structure
  Employee *p_ptr = &e;

  // access the structure's members using the pointer
  cout << "Name: " << p_ptr->name << endl;
  cout << "Age: " << p_ptr->age << endl;
  cout << "Salary: " << p_ptr->salary << endl;
  
  cout<<endl; 
  
  // assign values to the structure's members using the pointer 
  p_ptr->name = "Sahil";
  p_ptr->age = 35;
  p_ptr->salary = 55000.0;

  // access the structure's members using the pointer
  cout << "Name: " << e.name << endl;
  cout << "Age: " << e.age << endl;
  cout << "Salary: " << e.salary << endl;

  return 0;
}

Output

Name: John
Age: 30
Salary: 50000

Name: Sahil
Age: 35
Salary: 55000
In this example, we have created a pointer p_ptr to e using the & operator. The -> operator is used to access the members of the structure through the pointer.

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