what is the difference between pass by reference and pass by value in c Programming?

Question

pass by reference and pass by value in c Programming

Answer 1

First, let's look at an simple example:

=====================

#include <iostream>

using namespace std;

void add_by_value(int a)

{

a = a + 5;

}

void add_by_ref(int &a)

{

a = a + 5;

}

int main(int argc, char *argv[])

{

int a = 5;

cout << "Initial: " << a << endl;

add_by_value(a);

cout << "add_by_value: " << a << endl;

add_by_ref(a);

cout << "add_by_ref: " << a << endl;

}

======================

Run the code above, we get

Initial: 5

add_by_value: 5

add_by_ref: 10

Why do we have the result above?

1. Pass by value means a copy of the a is passed to add_by_value function. So while a is incremented in the function, it does not change the original variable a's value
2. Pass by reference means a reference pointer is passed to add_by_ref function. SO the addition is done on the original variable a. So the value is changed to 10.

I hope this explanation helps you to understand this concept.