Answers for "difference between reference and pointer c++"

pointers vs references in c++

#include<iostream>

/*
Pointers: *ptr, point to the memory location of a variable
int a = 10
int *ptr = &a //points to the location in memory (0x80ea or whatever) 
instead of the value

in order for pointers to work, the variable it's pointing to needs to 
be de-referenced using &.(If confused, remember that the variable, int a, 
is itself a reference to the location of the value you set it to).

A reference variable: &ref, points to another variable.

int b = 20;
int &ref = b // points to the value of b, which is 20.

run this if confused:
*/

    int a = 10;
    int *ptr = &a;
    std::cout << "int a value: " << a << std::endl;
    std::cout << "int ptr value: " << ptr << std::endl;

    int b = 20;
    int& ref = b;
    std::cout << "int b value: " << b << std::endl;
    std::cout << "int ref value: " << ref << std::endl;

    ref = a;
    std::cout << "int ref after setting it equal to a: " << ref << std::endl;
    ref = *ptr;
    std::cout << "int ref after setting it equal to *ptr: " << ref << std::endl;
    ptr = &ref;
    std::cout << "ptr after setting it equal to &ref: " << ptr << std::endl; 
    ptr = &b;
    std::cout << "ptr after setting it equal to &b: " << ptr << std::endl;

/*
Reference variables CANNOT be set to a pointer variable; In the case above, you 
see we can't just put ref = ptr; ptr HAS to be dereferenced with a *, which in 
turn will give us the value of a, or 10. (dereference pointers with *)

Same goes for pointer variables being set to a reference; you have to dereference 
the reference value (ptr = &b instead of ptr = b;). In the block above, when we 
set ptr = &ref, the ref variable is dereferenced showing us a memory location. 
When ptr=&b is called and we see the output, we noticed it is the same as the previous 
output.
*/

difference between pointer and reference

//Passing by Pointer://

// C++ program to swap two numbers using 
// pass by pointer. 
#include <iostream> 
using namespace std; 
  
void swap(int* x, int* y) 
{ 
    int z = *x; 
    *x = *y; 
    *y = z; 
} 
  
int main() 
{ 
    int a = 45, b = 35; 
    cout << "Before Swapn"; 
    cout << "a = " << a << " b = " << b << "n"; 
  
    swap(&a, &b); 
  
    cout << "After Swap with pass by pointern"; 
    cout << "a = " << a << " b = " << b << "n"; 
} 
o/p:
Before Swap
a = 45 b = 35
After Swap with pass by pointer
a = 35 b = 45

//Passing by Reference://

// C++ program to swap two numbers using 
// pass by reference. 
  
#include <iostream> 
using namespace std; 
void swap(int& x, int& y) 
{ 
    int z = x; 
    x = y; 
    y = z; 
} 
  
int main() 
{ 
    int a = 45, b = 35; 
    cout << "Before Swapn"; 
    cout << "a = " << a << " b = " << b << "n"; 
  
    swap(a, b); 
  
    cout << "After Swap with pass by referencen"; 
    cout << "a = " << a << " b = " << b << "n"; 
} 
o/p:
Before Swap
a = 45 b = 35
After Swap with pass by reference
a = 35 b = 45

//Difference in Reference variable and pointer variable//

References are generally implemented using pointers. A reference is same object, just with a different name and reference must refer to an object. Since references can’t be NULL, they are safer to use.

A pointer can be re-assigned while reference cannot, and must be assigned at initialization only.
Pointer can be assigned NULL directly, whereas reference cannot.
Pointers can iterate over an array, we can use ++ to go to the next item that a pointer is pointing to.
A pointer is a variable that holds a memory address. A reference has the same memory address as the item it references.
A pointer to a class/struct uses ‘->'(arrow operator) to access it’s members whereas a reference uses a ‘.'(dot operator)
A pointer needs to be dereferenced with * to access the memory location it points to, whereas a reference can be used directly.

difference between pointer and reference in c++

Pointers: 
A pointer is a variable that holds memory address of another variable. 
A pointer needs to be dereferenced with * operator to access the 
memory location it points to. 

References :
 A reference variable is an alias, that is, 
another name for an already existing variable.
 A reference, like a pointer, is also implemented 
by storing the address of an object.