Preclass Quiz

• after deleting ls.erase(it), 'it' will return the next element
• vector<int>::iterator it=ls.end();: returns an iterator pointing to the past-the-end element in the list container.

Defining Class

• Point

  Pointer transmit is more efficient than passing the whole structure.

• Why all these functions need to pass the point structure pointer?

  to make the function be more universally used, that is , dealing with all kinds of point structures.

• Migrate to C++

  move the function to the class, and make it a member function.
  '''cpp

struct Point
{
int x; int y; void setX(int x);
void setY(int y);
int getX();
int getY();
void print(); };
void Point::setX(int x)
{
this->x=x;
}

'''
'''cpp
void S::f(){
::f(); //call the global function f ::a++; //access the global variable a } '''
* the fetching critiria of the member function

this pointer: a pointer to the object that the member function is called on.
p.prt(); //Point::prt(&p);
the local variable will override the outer variable

Object

• Object: an instance of a class , attributes + service , data+operation

  encapsulation: data hiding

• object oriented programming:

  models designed can be used in multi-circumstances.
  rather, procedural programming is more like a one-time use.

• UML: Unified Modeling Language

• class is mostly the same with struct in cpp, but mostly...

• Every object has a type

• .h: header file, to be portable, the body of the class should be in the .cpp file, which are hidden from the user. Bear in mind the basic pinciple of encapsulation

Declaration and Definition

• a .cpp file is a compile unit
• Declaration:

  tells the compiler that the class exists, but not the details.

• Definition:

  tells the compiler the details of the class.

• the difference between <> and "" in the include statement:

  <>: search the system path, INCLUDE(environment variable), -I,
  "": search the current path, prior to the system path, then being similar to the <>
  open source libraries: put the opensource library in a particular path, and add the path to the INCLUDE environment variable.

• Standard header files:
  '''cpp

ifndef _POINT_H

define _POINT_H

endif

'''

• What if not initializing the object?

  no specific value

• init : not safe enough

• constructor:

  Point(): default constructor(without a parameter) , no return '''cpp

class Point
{
int x;
int y; Point(int x=0, int y=0); };
Point p(1,2);

'''
* initializer list

Point(int xx=0, int yy=0):x(xx),y(yy){}
the last is the inner constructer function to do initialization.