path: root/C++_from_the_Ground/Chapter_11(1).ipynb

{
 "metadata": {
  "name": "Chapter 11"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h1>Chapter 11: Introducing the Class<h1>"
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.1, Page Number: 249<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Illustration of a class in python'''\n\n#This creates the class queue\nclass queue:\n    #Initialize the queue \n    def __init__(self):\n        self.__sloc=0\n        self.__rloc=-1\n        self.__q=[]\n        \n    #Put an integer into the queue\n    def qput(self,i):\n        if self.__sloc==100:\n            print \"Queue is full.\"\n            return\n        self.__sloc+=1\n        self.__q.append(i)\n        \n    #Get an integer from the queue\n    def qget(self):\n        if self.__rloc==self.__sloc:\n            print \"Queue underflow\"\n            return\n        self.__rloc+=1\n        return self.__q[self.__rloc]     \n    \n\n    \n#Create two queue objects\nb=queue()\na=queue()\n\na.qput(10)\nb.qput(19)\n\na.qput(20)\nb.qput(1)\n\n#Result\nprint \"Contents of queue a: \",\nprint a.qget(),' ',a.qget()\n\nprint \"Contents of queue b: \",\nprint b.qget(),' ',b.qget()\n\n\n    \n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Contents of queue a:  10   20\nContents of queue b:  19   1\n"
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.2, Page Number: 250<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Demonstrate class member access'''\n    \nclass myclass:\n    def __init__(self):\n        self.__a=None  #private member\n        self.b=None    #public member\n    #public functions\n    def setlab(self,i):\n        self.__a=i      #refer to a\n        self.b=i*i    #refer to b\n        return\n    def geta(self):\n        return self.__a #refer to a\n    def reset(self):\n        #call setlab using self\n        self.setlab(0)     #the object is already known\n            \n        \nob=myclass()\nob.setlab(5)      #set ob.a and ob.b\nprint \"ob after setlab(5): \",ob.geta(),' ',\nprint ob.b #can access b because it is public\n\nob.b=20    #can access b because it is public\nprint \"ob after ob.b=20: \",\nprint ob.geta(),' ',ob.b\n\nob.reset()\nprint \"ob after ob.reset(): \",ob.geta(),' ',ob.b\n\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "ob after setlab(5):  5   25\nob after ob.b=20:  5   20\nob after ob.reset():  0   0\n"
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.3, Page Number: 254<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Demonstrate a constructor and a destructor'''\n#The destructors of python behave a little differently.\n\n#This creates the class queue\nclass queue:\n    \n    #Constructor\n    def __init__(self):      \n        self.__q=[]\n        self.__rloc=-1\n        self.__sloc=0\n        print \"Queue initialized\"\n        \n    #Destructor\n    def __del__(self):\n        print (\"Queue destroyed\")\n        \n    #Put an integer into the queue\n    def qput(self,i):\n        if self.__sloc == 100:\n            print \"Queue is full\"\n            return \n        self.__sloc+=1\n        self.__q.append(i)\n        \n    #Get an integer from the queue\n    def qget(self):\n        if self.__rloc==self.__sloc:\n            print \"Queue underflow\"\n            return\n        self.__rloc+=1\n        return self.__q[self.__rloc]\n        \n#Create two queue objects\na=queue()\n\n\na.qput(10)\na.qput(20)\nb=queue()\nb.qput(19)\n\nb.qput(1)\n\n#Result\nprint a.qget(),' ',\nprint a.qget(),' ',\nprint b.qget(),' ',\nprint b.qget(),' '\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Queue initialized\nQueue destroyed\nQueue initialized\nQueue destroyed\n10   20   19   1  \n"
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.4, Page Number: 257<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Parameterized Constructors'''\n\n#This creates the class queue\nclass queue:                            \n    \n    #Constructor\n    def __init__(self,i):      \n        self.__q=[]\n        self.__rloc=-1\n        self.__sloc=0\n        self.__who=i\n        print \"Queue \",self.__who,\" initialized.\"\n        \n    #Destructor\n    def __del__():\n        print \"Queue \",self.__who,\" destroyed\"\n        \n    #Put an integer into the queue\n    def qput(self,i):\n        if self.__sloc == 100:\n            print \"Queue is full\"\n            return \n        self.__sloc+=1\n        self.__q.append(i)\n        \n    #Get an integer from the queue\n    def qget(self):\n        if self.__rloc==self.__sloc:\n            print \"Queue underflow\"\n            return\n        self.__rloc+=1\n        return self.__q[self.__rloc]\n        \na=queue(1)\nb=queue(2)\n\na.qput(10)\nb.qput(19)\n\na.qput(20)\nb.qput(1)\n\n#Result\nprint a.qget(),' ',\nprint a.qget(),' ',\nprint b.qget(),' ',\nprint b.qget(),' '\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Queue  1  initialized.\nQueue destroyed\nQueue  2  initialized.\nQueue destroyed\n10   20   19   1  \n"
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.5, Page Number: 258<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Passing more than a single arguments'''\nclass widget:\n    \n    #Pass two arguments to the constructor\n    def __init__(self,a,b):\n        self.__i=a\n        self.__j=b\n        \n    def put_widget(self):\n        print self.__i,\" \",self.__j\n\n#Initializing\nx=widget(10,20)\ny=widget(0,0)\n\nx.put_widget()\ny.put_widget()\n\n    ",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "10   20\n0   0\n"
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.6, Page Number: 259<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''An example of class'''\n\nclass myclass:\n    \n    #Constructor\n    def __init__(self,x):\n        self.a=x\n    #To get the vale of a\n    def get_a(self):\n        return self.a\n\n#Initializing\nob=myclass(4)\n\n#Result\nprint ob.get_a()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "4\n"
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.7, Page Number: 260<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Using structures to create a class'''\n\nfrom ctypes import *\n\nclass c1(Structure):\n    _fields_=[(\"__i\", c_int)]  #private member\n    def get_i(self):           #public finctions\n        return self.__i\n    def put_i(self,j):\n        self.__i=j\n\n#Variable declaration\ns=c1()\n\ns.put_i(10)\n\n#Result\nprint s.get_i()\n        \n    ",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "10\n"
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.8, Page Number: 261<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Now we use class instead'''\n\nclass c1:\n    def __init__(self):\n        self.__i=None   #private member\n    def get_i(self):    #public finctions\n        return self.__i\n    def put_i(self,j):\n        self.__i=j\n\n#Variable declaration\ns=c1()\n\ns.put_i(10)\n\n#Result\nprint s.get_i()\n        \n    ",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "10\n"
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.9, Page Number: 263<h3> "
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Create a union-based class'''\n\nfrom ctypes import *\n\n#Creates a union\nclass u_type(Union):\n    _fields_ = [(\"i\",c_short),\n            (\"ch\", c_char*2)]\n    #Constructor\n    def __init__(self,a):\n        self.i=a\n        \n    #Show the characters that comprise a short int.\n    def showchars(self):\n        print self.ch[0]\n        print self.ch[1]\n        \n        \nu=u_type(1000)\n\n#Displays char of 1000\nu.showchars()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "\ufffd\n\u0003\n"
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.10, Page Number: 264<h3> "
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''A simple class program'''\n#There is no inline function in python\n\nclass c1:\n    def __init__(self):\n        self.__i=None\n    def get_i(self):\n        return self.i\n    def put_i(self,j):\n        self.i=j\n\n#Variable declaration\ns=c1()\n\ns.put_i(10)\n\n#Result\nprint s.get_i()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "10\n"
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.11, Page Number: 265<h3> "
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''A simple class program'''\n#There is no inline functions in python\n\nclass c1:\n    def __init__(self):\n        self.__i=None\n    def get_i(self):\n        return self.i\n    def put_i(self,j):\n        self.i=j\n\n#Variable declaration\ns=c1()\n\ns.put_i(10)\n\n#Result\nprint s.get_i()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "10\n"
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.12, Page Number: 267<h3> "
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''An example of arrays of objects'''\n\nclass display:\n    def __init__(self):\n        width=None\n        height=None\n        res=None\n    def set_dim(self,w,h):\n        self.width=w\n        self.height=h\n    def get_dim(self):\n        return self.width,self.height\n    def set_res(self,r):\n        self.res=r\n    def get_res(self):\n        return self.res\n        \n#Variable decleration\nnames=[\"low\",\"medium\",\"high\"]   \n(low,medium,high)=(0,1,2)    #For enumeration type\nw=None\nh=None\ndisplay_mode=[]*3\n\nfor i in range(3):\n    display_mode.append(display())\n\n#Initialize the array of objects using member functions\ndisplay_mode[0].set_res(low)\ndisplay_mode[0].set_dim(640,480)\n\ndisplay_mode[1].set_res(medium)\ndisplay_mode[1].set_dim(800,600)\n\ndisplay_mode[2].set_res(high)\ndisplay_mode[2].set_dim(1600,1200)\n\n#Result\nprint \"Available display modes: \"\nfor i in range(3):\n    print names[display_mode[i].get_res()],\" : \",\n    w,h=display_mode[i].get_dim()\n    print w,\" by \",h",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Available display modes: \nlow  :  640  by  480\nmedium  :  800  by  600\nhigh  :  1600  by  1200\n"
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.13, Page Number: 268<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Initialize an array of objects'''\n\nclass samp:\n    __a=None\n    def __init__(self,n):\n        self.__a=n\n    def get_a(self):\n        return self.__a\n\n#Initializing the list\nsampArray=[samp(-1),samp(-2),samp(-3),samp(-4)]\n\n#Display\nfor i in range(4):\n    print sampArray[i].get_a(),' ',",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "-1   -2   -3   -4  \n"
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.14, Page Number: 269<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Two dimensional array if objects'''\n\nclass samp:\n    __a=None\n    __b=None\n    def __init__(self,n,m):\n        self.__a=n\n        self.__b=m\n    def get_a(self):\n        return self.__a\n    def get_b(self):\n        return self.__b\n \n#Initializing the list\nsampArray=[[samp(1,2),samp(3,4)],\n           [samp(5,6),samp(7,8)],\n           [samp(9,10),samp(11,12)],\n           [samp(13,14),samp(15,16)]]\n\n#Display\nfor i in range(4):\n    print sampArray[i][0].get_a(),' ',\n    print sampArray[i][0].get_b()\n    print sampArray[i][1].get_a(),' ',\n    print sampArray[i][1].get_b()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "1   2\n3   4\n5   6\n7   8\n9   10\n11   12\n13   14\n15   16\n"
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.15, Page Number: 270<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''A simple example using an object pointer'''\n\nfrom ctypes import *\n\nclass P_example(Structure):\n    __num=None\n    def set_num(self,val):\n        self.__num=val\n    def show_num(self):\n        print self.__num\n\n#Variable declaration\nob=P_example()          #Declare an object to the structure\np=POINTER(P_example)    #Declare a pointer to the structure\n\nob.set_num(1)           #access ob directly\nob.show_num()\n\np=ob                    #assign p the address of ob\np.show_num()            #access ob using pointer\n        \n        ",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "1\n1\n"
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": "<h3>Example 11.16, Page Number: 271<h3>"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''Pointer to array of objects'''\n\nclass P_example(Structure):\n    __num=None\n    def set_num(self,val):\n        self.__num=val\n    def show_num(self):\n        print self.__num\n        \n#Variable declaration\nob=[P_example(),P_example()]          #Declare an object to the structure\np=POINTER(P_example)                  #Declare a pointer to the structure\n\nob[0].set_num(10)                     #access objects directly\nob[1].set_num(20)\n\np=ob                             #obtain pointer to first element\np[0].show_num()                  #access ob using pointer\n\np[1].show_num()\n\np[0].show_num()\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "10\n20\n10\n"
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "",
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}