2-1什么是面向对象

What is object? 
object=entity
object may be
        visible
        invisible
Object is variable in programming language.

Object=attributes+services
Data:the properties or status
Operation:the functions

Mapping
From the problem space to the solution one. ​​​​​​​

 C vs. C++
C doesn't support relationship btw data and functions. 
typedef struct point3d{
float x;
float y;
float z;
}Point3d;

void Point3d_print(const Point3d* pd);

Point3d a;
a.x=1;a

2-1什么是面向对象最先出现在Python成神之路。