Data Types C++ Tutorial

#include 
using std::cout;
using std::endl;
#include 
using std::strlen;                        
int main()
{
   char *string1 = "asdfasdfasdfasdf";
   char *string2 = "     f    ";
   char *string3 = "       ";
   cout << "The length of \"" << string1 << "\" is " << strlen( string1 )
      << "\nThe length of \"" << string2 << "\" is " << strlen( string2 )
      << "\nThe length of \"" << string3 << "\" is " << strlen( string3 ) 
      << endl;
   return 0;
}
The length of "asdfasdfasdfasdf" is 16
The length of " f " is 10
The length of " " is 7