example-pass-by.cpp

#include <iostream>
using namespace std;

// C++ prototypes 
void pass_by_reference(int &var_1);
void pass_by_value(int var_1);

// example-pass-by.cpp
// Illustrating pass by reference and value 
// using C++ 

// Function declarations
void pass_by_reference(int &var_1)
{
    var_1 = var_1 + 5;
    cout << var_1 << "\n";
}

void pass_by_value(int var_1)
{
    var_1 = var_1 + 10;
    cout << var_1 << "\n";
}

// Program entry point
int main ()
{
    int var_1 = 20;
    cout << "The initial value of var_1 is: " << var_1 << "\n";

    // This preserves the memory address and it 
    // will keep the value.
    cout << "This is after it's passed by reference:" << "\n";
    pass_by_reference(var_1);
    cout << var_1 << "\n";
    
    // This doesn't preserve the memory address 
    // and passes a copy of the value
    cout << "This is after it's passed by Value." << "\n"; 
    pass_by_value(var_1);
    cout << var_1 << "\n";
}