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C++ Pointers and References

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Reference vs Pointers

References and pointers provide indirect access to variable values. but they have some key differences, as well as pros and cons.

Syntax

  • Pointers are declared using the * symbol;

  • References are declared using the & symbol.

Initialization

You can't declare an empty reference. But you can declare an empty pointer with nullptr.

Reassignment

References can't be re-assigned to refer to a different object.

cpp

main

copy
#include <iostream>

int main()
{
int x = 125, y = 500;
// creating a reference to x variable
int& ref_x = x;
ref_x = y; // attempt to re-assigned ref_x
ref_x = 0;
std::cout << x << ' ' << y;
}

              
12345678910111213

            
#include <iostream>

int main() 
{
    int x = 125, y = 500;
    
    // creating a reference to x variable
    int& ref_x = x;
    ref_x = y; // attempt to re-assigned ref_x
    ref_x = 0;
    
    std::cout << x << ' ' << y;
}

Pointers can be re-assigned to point to different memory locations

cpp

main

copy
#include <iostream>

int main()
{
int x = 125, y = 500;
// creating a pointer to x variable
int* ptr = &x;
ptr = &y; // attempt to re-assigned ref_x
*ptr = 0;
std::cout << x << ' ' << y;
}

              
12345678910111213

            
#include <iostream>

int main() 
{
    int x = 125, y = 500;
    
    // creating a pointer to x variable
    int* ptr = &x;
    ptr = &y; // attempt to re-assigned ref_x
    *ptr = 0;
    
    std::cout << x << ' ' << y;
}

Accessing the value

To access the value pointed by a pointer, you use the dereference operator *. For references, you don't need to use any special operator; you simply use the reference variable directly.

Both pointers and references are crucial in memory management, contributing to the flexibility of programs. Their usage depends on the context.

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Section 3. Chapter 4
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