The do while loop, Example
int x = 0, n = 15;
int fact = 1;
do
{
x = x + 1;
fact = fact*x;
}while(x < n);
cout << fact;
int x = 0, n = 15;
int fact = 1;
while( x < n)
{
x = x + 1;
fact = fact*x;
}
cout << fact;