Passing by Reference Vs. Passing by the pointer in C++
Passing by Reference Vs. Passing by the pointer in C++
Throughout C++, it can transfer parameter values except by pointers or through referring to a function. For both cases, we have the same result. So the remaining statements are inevitable; when one is over the other significant? What are the causes we’re using one over another?
Passing by Pointer:
// C++ program for swaping two numbers with pass-by-pointer.
#include <iostream>
using namespace std;
void swap(int* t, int* p)
{
int k = *t;
*t = *p;
*p = k;
}
int main()
{
int s = 78, c = 55;
cout << "Before Swap\n";
cout << "s = " << s << " c = " << c << "\n";
swap(&s, &c);
cout << "After Swap with pass by pointer\n";
cout << "s = " << s << " c = " << c << "\n";
}
Output:
Passing by Reference:
// C++ program to swap two numbers using
// pass by reference.
#include <iostream>
using namespace std;
void swap(int& w, int& q)
{
int l = w;
w = q;
q = l;
}
int main()
{
int n = 122, m = 210;
cout << "Before Swap\n";
cout << "n = " << n << " m = " << m << "\n";
swap(n, m);
cout << "After Swap with pass by reference\n";
cout << "n = " << n << " m = " << m << "\n";
}
Output:
The difference in between Reference variable and pointer variable
- Generally, references are applied with pointers. A reference is the same object; it only has to refer to an entity with a different name and context. They are safer to use as references cannot be NULL.
- A pointer may be reassigned while the relation cannot be assigned and must only be allocated at initialization.
- The pointer is explicitly assignable to NULL, while reference cannot.
- Pointers may append over an array, and we can use + + to move towards the next object a pointer points toward.
- The variable is a way that has an address to the memory. A reference has the same address as the object it is referring to.
- A class or struct pointer requires' ->'(arrow operator) to reach its members while a reference uses a. '(dot operator)
- To access the memory location it refers to, a pointer must be dereferenced with *, while a pointer can be substituted directly.
// C++ program to display variations between reference and pointer.
#include <iostream>
using namespace std;
struct demo
{
int s;
};
int main()
{
int m = 3;
int n = 8;
demo d;
int *k;
k = &m;
k = &n; // 1. Pointer reintialization allowed
int &t = m;
// &r = y; // 1. Compile Error
t = n; // 1. m value becomes 3
k = NULL;
// &r = NULL; // 2. Compile Error
k++; // 3. Points to next memory location
t++; // 3. m values becomes 8
cout << &k << " " << &m << endl; // 4. Different address
cout << &t << " " << &m << endl; // 4. Same address
demo *q = &d;
demo &qq = d;
q->s = 9;
// q.s = 9; // 5. Compile Error
qq.s = 9;
// qq->s = 9; // 5. Compile Error
cout << k << endl;
cout << t << endl;
return 0;
}
Output:
