> May I ask you how should I compile it through VC++?
Like you already are, but without that warning?

Dunno - declare 'i' before you enter the switch statement, not when you declare the for loop.

Or perhaps
Code:
case 4: 
{ // spoof an extra scope 
     for(int i = 1; i < argc; i++)
     cout << "Argument " << i << " is " << argv[i] << endl;
}
break;
Compiler's broken - the rest is hackery