for( initialization; test-condition; increment ) {
  statement-list;
  }
The for construct is a general looping mechanism consisting of 4 parts:
For example:
   for( int i = 0; i < 10; i++ ) {
     cout << "i is " << i << endl;
   }
   int j, k;
   for( j = 0, k = 10;
        j < k;
        j++, k-- ) {
     cout << "j is " << j << " and k is " << k << endl;
   }
   for( ; ; ) {
     // loop forever!
   }