path: root/C++_from_the_Ground/Chapter_11.ipynb

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  {
   "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": [
      "\n",
      "\n",
      "class 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\n",
      "b=queue()\n",
      "a=queue()\n",
      "\n",
      "a.qput(10)\n",
      "b.qput(19)\n",
      "\n",
      "a.qput(20)\n",
      "b.qput(1)\n",
      "\n",
      "#Result\n",
      "print \"Contents of queue a: \",\n",
      "print a.qget(),' ',a.qget()\n",
      "\n",
      "print \"Contents of queue b: \",\n",
      "print b.qget(),' ',b.qget()\n",
      "\n",
      "\n",
      "    \n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Contents of queue a:  10   20\n",
        "Contents 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": [
      "\n",
      "    \n",
      "class 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",
      "        \n",
      "ob=myclass()\n",
      "ob.setlab(5)      #set ob.a and ob.b\n",
      "print \"ob after setlab(5): \",ob.geta(),' ',\n",
      "print ob.b #can access b because it is public\n",
      "\n",
      "ob.b=20    #can access b because it is public\n",
      "print \"ob after ob.b=20: \",\n",
      "print ob.geta(),' ',ob.b\n",
      "\n",
      "ob.reset()\n",
      "print \"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\n",
        "ob after ob.b=20:  5   20\n",
        "ob 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": [
      "\n",
      "class 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\n",
      "a=queue()\n",
      "\n",
      "\n",
      "a.qput(10)\n",
      "a.qput(20)\n",
      "b=queue()\n",
      "b.qput(19)\n",
      "\n",
      "b.qput(1)\n",
      "\n",
      "#Result\n",
      "print a.qget(),' ',\n",
      "print a.qget(),' ',\n",
      "print b.qget(),' ',\n",
      "print b.qget(),' '\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Queue initialized\n",
        "Queue destroyed\n",
        "Queue initialized\n",
        "Queue destroyed\n",
        "10   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": [
      "\n",
      "\n",
      "class 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",
      "        \n",
      "a=queue(1)\n",
      "b=queue(2)\n",
      "\n",
      "a.qput(10)\n",
      "b.qput(19)\n",
      "\n",
      "a.qput(20)\n",
      "b.qput(1)\n",
      "\n",
      "#Result\n",
      "print a.qget(),' ',\n",
      "print a.qget(),' ',\n",
      "print b.qget(),' ',\n",
      "print b.qget(),' '\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Queue  1  initialized.\n",
        "Queue destroyed\n",
        "Queue  2  initialized.\n",
        "Queue destroyed\n",
        "10   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": [
      "\n",
      "class 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\n",
      "x=widget(10,20)\n",
      "y=widget(0,0)\n",
      "\n",
      "x.put_widget()\n",
      "y.put_widget()\n",
      "\n",
      "    "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10   20\n",
        "0   0\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 11.6, Page Number: 259<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class 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\n",
      "ob=myclass(4)\n",
      "\n",
      "#Result\n",
      "print 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": [
      "\n",
      "\n",
      "from ctypes import *\n",
      "\n",
      "class 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\n",
      "s=c1()\n",
      "\n",
      "s.put_i(10)\n",
      "\n",
      "#Result\n",
      "print 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": [
      "\n",
      "class 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\n",
      "s=c1()\n",
      "\n",
      "s.put_i(10)\n",
      "\n",
      "#Result\n",
      "print 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": [
      "\n",
      "\n",
      "from ctypes import *\n",
      "\n",
      "#Creates a union\n",
      "class 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",
      "        \n",
      "u=u_type(1000)\n",
      "\n",
      "#Displays char of 1000\n",
      "u.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": [
      "\n",
      "class 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\n",
      "s=c1()\n",
      "\n",
      "s.put_i(10)\n",
      "\n",
      "#Result\n",
      "print 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": [
      "\n",
      "\n",
      "class 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\n",
      "s=c1()\n",
      "\n",
      "s.put_i(10)\n",
      "\n",
      "#Result\n",
      "print 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": [
      "\n",
      "\n",
      "class 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\n",
      "names=[\"low\",\"medium\",\"high\"]   \n",
      "(low,medium,high)=(0,1,2)    #For enumeration type\n",
      "w=None\n",
      "h=None\n",
      "display_mode=[]*3\n",
      "\n",
      "for i in range(3):\n",
      "    display_mode.append(display())\n",
      "\n",
      "#Initialize the array of objects using member functions\n",
      "display_mode[0].set_res(low)\n",
      "display_mode[0].set_dim(640,480)\n",
      "\n",
      "display_mode[1].set_res(medium)\n",
      "display_mode[1].set_dim(800,600)\n",
      "\n",
      "display_mode[2].set_res(high)\n",
      "display_mode[2].set_dim(1600,1200)\n",
      "\n",
      "#Result\n",
      "print \"Available display modes: \"\n",
      "for 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: \n",
        "low  :  640  by  480\n",
        "medium  :  800  by  600\n",
        "high  :  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": [
      "\n",
      "\n",
      "class 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\n",
      "sampArray=[samp(-1),samp(-2),samp(-3),samp(-4)]\n",
      "\n",
      "#Display\n",
      "for 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": [
      "\n",
      "\n",
      "class 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\n",
      "sampArray=[[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\n",
      "for 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\n",
        "3   4\n",
        "5   6\n",
        "7   8\n",
        "9   10\n",
        "11   12\n",
        "13   14\n",
        "15   16\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 11.15, Page Number: 270<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "from ctypes import *\n",
      "\n",
      "class 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\n",
      "ob=P_example()          #Declare an object to the structure\n",
      "p=POINTER(P_example)    #Declare a pointer to the structure\n",
      "\n",
      "ob.set_num(1)           #access ob directly\n",
      "ob.show_num()\n",
      "\n",
      "p=ob                    #assign p the address of ob\n",
      "p.show_num()            #access ob using pointer\n",
      "        \n",
      "        "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1\n",
        "1\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 11.16, Page Number: 271<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "class 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\n",
      "ob=[P_example(),P_example()]          #Declare an object to the structure\n",
      "p=POINTER(P_example)                  #Declare a pointer to the structure\n",
      "\n",
      "ob[0].set_num(10)                     #access objects directly\n",
      "ob[1].set_num(20)\n",
      "\n",
      "p=ob                             #obtain pointer to first element\n",
      "p[0].show_num()                  #access ob using pointer\n",
      "\n",
      "p[1].show_num()\n",
      "\n",
      "p[0].show_num()\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10\n",
        "20\n",
        "10\n"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}