Le système n'est pas déclaré dans le champ d'application?

Je sais que c'est un code simple, Comment puis-je réparer "le Système n'est pas déclaré dans la portée du problème?

#include<iostream>
using namespace std;
int main(void)
{
system ( "TITLE Calculator" );
system ( "COLOR 2" );
char cChar;
double dfirstnumber;
double dsecondnumber;
char cDoagain;
do
{
system("CLS");
cout << "Please enter the first number you would like to use."<< endl;
cin >> dfirstnumber;
cout<< "Please enter the operation you would like to perform." << " (+,-,*,or /)" << endl;
cin >> cChar;
cout<< "Please enter the second number you would like to use." << endl;
cin >> dsecondnumber;
switch (cChar)
{
case '+':
cout << "The answer is: " << dfirstnumber << "+" << dsecondnumber << "=" <<
(dfirstnumber + dsecondnumber) << endl;
break;
case '-':
cout << "The answer is: " << dfirstnumber << "-" << dsecondnumber << "=" <<
(dfirstnumber - dsecondnumber) << endl;
break;
case '*':
cout << "The answer is: " << dfirstnumber << "*" << dsecondnumber << "=" <<
(dfirstnumber * dsecondnumber) << endl;
break;
case 'x':
cout << "The answer is: " << dfirstnumber << "x" << dsecondnumber << "=" <<
(dfirstnumber * dsecondnumber) << endl;
break;
case 'X':
cout << "The answer is: " << dfirstnumber << "X" << dsecondnumber << "=" <<
(dfirstnumber * dsecondnumber) << endl;
break;
case '/':
if(dsecondnumber == 0){
cout<< "That is an invalid operation." << endl;}
else{
cout << "The answer is: " << dfirstnumber << "/" << dsecondnumber << "=" <<
(dfirstnumber / dsecondnumber) << endl;
}
break;
default:
cout << "That is an invalid operation." << endl;
break;
}
cout << "Would you like to start again? (Y/N)" << endl;
cin >>  cDoagain;
}while (cDoagain == 'Y' or cDoagain == 'y');
system("PAUSE");
return 0;
}

Heres mon message de fin:

C:\Documents and Settings\Nil\Mes Documents\Travail\Test\main.rpc||
la fonction " int main()':| C:\Documents and Settings\Nil\Mes
Documents\Travail\Test\main.rpc|8|erreur: "système" n'a pas été déclarée dans
cette étendue||

|=== Build finished: 1 errors, 0 avertissements ===|

OriginalL'auteur Nilo Cortex | 2010-10-07