#include <iostream.h>

int firstnum;    // create a global variable named firstnum

void valfun();   // function prototype (declaration)

int main()
{
  int secnum;    // create a local variable named secnum

  firstnum = 10; // store a value into the global variable
  secnum = 20;   // store a value into the local variable

  cout << "From main(): firstnum = " << firstnum << endl;
  cout << "From main(): secnum =  " << secnum << endl;

  valfun();      // call the function valfun

  cout << "\nFrom main() again: firstnum = " << firstnum << endl;
  cout << "From main() again: secnum = " << secnum << endl;

  return 0;
}

void valfun()   // no values are passed to this function
{
  int secnum;  // create a second local variable named secnum

  secnum = 30; // this only affects this local variable's value

  cout << "\nFrom valfun(): firstnum = " << firstnum << endl;
  cout << "\nFrom valfun(): secnum = " << secnum << endl;

  firstnum = 40;    // this changes firstnum for both functions

  return;
}