CS 131 Function Exercises (answers)

Identify for each of the following:
    local and global variables
    value and reference parameters
    the output

//*********Example 1*********
#include <iostream>
using namespace std;
void change();
int main ()
{
   int x;    //local
   x = 0;
   change();
   cout << x;
   return 0;
}
void change()
{
   x = 1;
}

OUTPUT:  error when compiling, 'x' : undeclared identifier


//*********Example 2*********
#include <iostream>
using namespace std;
void change();
int x;    //global
int main ()
{
   x = 0;
   change();
   cout << x;
   return 0;
}
void change()
{
   x = 1;
}

OUTPUT:  1

//*********Example 3*********
#include <iostream>
using namespace std;
void change();
int x;    //global
int main ()
{
   x = 0;
   change();
   cout << x;
   return 0;
}
void change()
{
   int x;
   x = 1;
}

OUTPUT:  0

//*********Example 4*********
#include <iostream>
using namespace std;
void change(int);
int main ()
{
   int x;    //local
   x = 0;
   change(x);       //argument x
   cout << x;
   return 0;
}
void change(int y)  //value parameter y
{
   y = 1;
}

OUTPUT:  0

//*********Example 5*********
#include <iostream>
void change(int&);
int main ()
{
   int x;    //local
   x = 0;
   change(x);        //argument x
   cout << x;
   return 0;
}
void change(int& y)  //reference parameter y
{
   y = 1;
}

OUTPUT:  1