//2.3.1 Source code
//prob3.cpp
#include <iostream>
using namespace std;

//---------------------------------------------------------------------------
void f1(int x) {                //pass by value
x -= 10;
cout << "In: " << x << endl;
}

void f2(int &x) {               //pass by reference
x -= 10;
cout << "In: " << x << endl;
}

void f3(int const &x) {         // pass by const reference
int z = x - 10;
cout << "In: " << x << endl << "or " << z << " after mod" << endl;
}

void f4(int *x) {               // pass by const reference
*x -= 10;
cout << "In: " << *x << endl;
}
//---------------------------------------------------------------------------
void main() {
int x = 100;
cout << "Pass to a function by value"<<endl;
cout << "Before: " << x <<endl;
f1(x);
cout << "After: " << x <<endl;

cout << "Pass to a function by reference"<<endl;
cout << "Before: " << x <<endl;
int &refX = x;
f2(refX);
cout << "After: " << x <<endl;

cout << "Pass to a function by const reference"<<endl;
cout << "Before: " << x <<endl;
f3(x);
cout << "After: " << x <<endl;

cout << "Pass to a function by pointer/address"<<endl;
cout << "Before: " << x <<endl;
int *pX = &x;
f4(pX);
cout << "After: " << x <<endl;

system("pause");
}
//---------------------------------------------------------------------------