C++ Pointers

Pointers in C++ are variables that store memory addresses, allowing direct access to data locations rather than the data itself.

Retrieving Memory Addresses

To retrieve a variable’s memory address, use the & (address-of) operator.

Example: Getting the Memory Address of a Variable

#include <iostream>
using namespace std;

int main() {
    string motorcycleBrand = "Harley-Davidson";  

    cout << motorcycleBrand << "\n";  // Outputs Harley-Davidson  
    cout << &motorcycleBrand << "\n";  // Outputs the memory address (e.g., 0x6dfed4)  

    return 0;
}

#include <iostream>

using namespace std;

​

int main() {

    string motorcycleBrand = "Harley-Davidson";  

​

    cout << motorcycleBrand << "\n";  // Outputs Harley-Davidson  

    cout << &motorcycleBrand << "\n";  // Outputs the memory address (e.g., 0x6dfed4)  

​

    return 0;

}

​

Instead of displaying the value, &motorcycleBrand prints its memory location.

Creating a Pointer

Pointers store memory addresses rather than direct values. Declare a pointer using the * (asterisk) operator and assign it the address of another variable.

Example: Assigning a Pointer

#include <iostream>
using namespace std;

int main() {
    string motorcycleBrand = "Harley-Davidson";  
    string* ptr = &motorcycleBrand;  // Pointer storing the address of motorcycleBrand  

    cout << motorcycleBrand << "\n";  // Outputs Harley-Davidson  
    cout << &motorcycleBrand << "\n";  // Outputs memory address (e.g., 0x6dfed4)  
    cout << ptr << "\n";  // Outputs memory address stored in ptr  

    return 0;
}

#include <iostream>

using namespace std;

​

int main() {

    string motorcycleBrand = "Harley-Davidson";  

    string* ptr = &motorcycleBrand;  // Pointer storing the address of motorcycleBrand  

​

    cout << motorcycleBrand << "\n";  // Outputs Harley-Davidson  

    cout << &motorcycleBrand << "\n";  // Outputs memory address (e.g., 0x6dfed4)  

    cout << ptr << "\n";  // Outputs memory address stored in ptr  

​

    return 0;

}

​

Now, ptr holds the memory address of motorcycleBrand.

Understanding Pointer Declaration

When declaring a pointer, you may see different formatting styles. All are valid, but string* myString; is preferred for clarity:

string* myString;  // Preferred
string *myString;
string * myString;

string* myString;  // Preferred

string *myString;

string * myString;

​

The type of the pointer must match the type of the variable it points to.