// HINTS5.cpp. Illustration of side effects with
// global variable 

#include <iostream> 

using namespace std;

int globalVar; 	// POOR DESIGN: a global variable

int main()
{
   void tripleGlobalVar();
   void displayGlobalVarTensDigit();

   globalVar = 125;
   cout << "The tens digit is ";
   displayGlobalVarTensDigit();
   tripleGlobalVar();
   cout << " ,but the tens digit of the triple is ";
   displayGlobalVarTensDigit();
   cout << "." << endl;

   return 0;
}

//
// This routine triples the global variable globalVar
//

void tripleGlobalVar()
{
   globalVar = 3 * globalVar;
}

//
// This routine displays the tens digit of globalVar and
// produces a side effect
//

void displayGlobalVarTensDigit()
{
   globalVar = (globalVar / 10) % 10; // SIDE EFFECT
   cout << globalVar;
}