1.1.13.6 Output

• For cout, It can recognize type automatically, and It is extensible, You can redefine << operator so that cout can recognize you data type.
  class Foo{ 
  friend ostream & operator<<(ostream& s, const Foo &r); 
  } 
   
  ostream & operator<<(ostream& s, const Foo &r){ 
  s<<Foo.a<<Foo.b<<endl; 
  }
• How to print pointer address?
  char* amount = "dozen"; 
  cout<< amount  ; //print "dozen" string 
   
  cout<<(void*) amount;   //prints the address of pointer 
  printf("%p", (void*) p);
• Format is key point for Output. you need to know the common manipulator to control the output format.
• Number base manipulators: hex, oct and dec; Field widths: Width, fill, precision Setf()
• You don’t need to know the details, just name of them. When you want to use them go to reference website to look.A detail format manipulators can be seen on C++ primer P1090. You need to include <iomanip>
• << is a bitwise left-shift operator in C language, but in C++, we overloaded it in ostream class, cout is a object of ostream,
• You can use cout<<flush to force flushing the output buffer
• cout.write can be used to output a string, It will output certain length string, even reach the end of string.