{
 "metadata": {
  "name": ""
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Chapter 7: Pointers"
     ]
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.1, page no. 266"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "A simple program using pointers\n",
      "note: there are no pointers in Python.\n",
      "\"\"\"\n",
      "\n",
      "import sys\n",
      "\n",
      "number = 10;\n",
      "print \"number's address: \", id(number)\n",
      "print \"number's value: \", number\n",
      " \n",
      "pnumber = id(number)\n",
      "print \"pnumber's address: \", id(pnumber)\n",
      "print \"pnumber's size: %d bytes\" %(sys.getsizeof(pnumber))\n",
      "print \"pnumber's value: \", pnumber\n",
      "print \"value pointed to: \", number"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "number's address:  42843088\n",
        "number's value:  10\n",
        "pnumber's address:  54575640\n",
        "pnumber's size: 24 bytes\n",
        "pnumber's value:  42843088\n",
        "value pointed to:  10\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.2, page no. 270"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "What's the pointer of it all\n",
      "\"\"\"\n",
      "\n",
      "num1 = 0\n",
      "num2 = 0\n",
      "pnum = None\n",
      " \n",
      "pnum = id(num1)\n",
      "num1 = 2\n",
      "num2 += 1\n",
      "num2 += num1\n",
      "pnum = id(num2)\n",
      "num2 += 1\n",
      "print \"num1 = %d num2 = %d pnum = %d pnum + num2 = %d\" %(num1, num2, pnum, pnum + num2)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "num1 = 2 num2 = 4 pnum = 42843256 pnum + num2 = 42843260\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.3, page no. 272"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Using pointer arguments to scanf_s\n",
      "note: in Python you cannot use pointers to input a value\n",
      "\"\"\"\n",
      "\n",
      "print \"Input an integer: \",\n",
      "value = int(raw_input())\n",
      "print \"You entered: \", value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Input an integer: "
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "7\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " You entered:  7\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.4, page no. 276"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Arrays and pointers\n",
      "\"\"\"\n",
      "\n",
      "multiple = ['M', 'y','s','t', 'r', 'i', 'n', 'g']\n",
      " \n",
      "p = id(multiple[0])\n",
      "print \"The address of the first array element : \", p\n",
      "p = id(multiple)\n",
      "print \"The address obtained from the array name: \", p"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "The address of the first array element :  140170253709440\n",
        "The address obtained from the array name:  58009432\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.5, page no. 277"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Incrementing a pointer to an array\n",
      "\"\"\"\n",
      "\n",
      "multiple = \"a string\"\n",
      "p = multiple\n",
      " \n",
      "for i in range(len(multiple)):\n",
      "    print \"multiple[%d] = %c *(p+%d) = %c id(multiple[%d]) = %d p+%d = %d \" %(i, multiple[i], i, p[i], i, id(multiple[i]), i, id(p[i]))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "multiple[0] = a *(p+0) = a id(multiple[0]) = 140170254071168 p+0 = 140170254071168 \n",
        "multiple[1] =   *(p+1) =   id(multiple[1]) = 140170254278248 p+1 = 140170254278248 \n",
        "multiple[2] = s *(p+2) = s id(multiple[2]) = 140170254071048 p+2 = 140170254071048 \n",
        "multiple[3] = t *(p+3) = t id(multiple[3]) = 140170254070208 p+3 = 140170254070208 \n",
        "multiple[4] = r *(p+4) = r id(multiple[4]) = 140170254275768 p+4 = 140170254275768 \n",
        "multiple[5] = i *(p+5) = i id(multiple[5]) = 140170254277248 p+5 = 140170254277248 \n",
        "multiple[6] = n *(p+6) = n id(multiple[6]) = 140170254276568 p+6 = 140170254276568 \n",
        "multiple[7] = g *(p+7) = g id(multiple[7]) = 140170254073528 p+7 = 140170254073528 \n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.6, page no. 277"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Incrementing a pointer to an array of integers\n",
      "\"\"\"\n",
      "\n",
      "import sys\n",
      "\n",
      "multiple = [15, 25, 35, 45]\n",
      "p = multiple\n",
      " \n",
      "for i in range(sys.getsizeof(multiple)/sys.getsizeof(multiple[0])):\n",
      "    print \"address p+%d (id(multiple[%d])): %d *(p+%d) value: %d\" %( i, i, id(p[i]), i, p[i])\n",
      " \n",
      "print \"Type integer occupies: %d bytes\" %sys.getsizeof(int())"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "address p+0 (id(multiple[0])): 42842968 *(p+0) value: 15\n",
        "address p+1 (id(multiple[1])): 42842728 *(p+1) value: 25\n",
        "address p+2 (id(multiple[2])): 42842488 *(p+2) value: 35\n",
        "address p+3 (id(multiple[3])): 42844240 *(p+3) value: 45\n",
        "Type integer occupies: 24 bytes\n"
       ]
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.7, page no. 279"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Two-dimensional arrays and pointers\n",
      "\"\"\"\n",
      "\n",
      "board = [['1','2','3'],\n",
      "         ['4','5','6'],\n",
      "         ['7','8','9']]\n",
      "print \"address of board : \", id(board)\n",
      "print \"address of board[0][0] : \", id(board[0][0])\n",
      "print \"value of board[0]: \", board[0]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "address of board :  58026608\n",
        "address of board[0][0] :  140170254070808\n",
        "value of board[0]:  ['1', '2', '3']\n"
       ]
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.7A, page no. 280"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Two-dimensional arrays and pointers\n",
      "\"\"\"\n",
      "\n",
      "board = [['1','2','3'],\n",
      "         ['4','5','6'],\n",
      "         ['7','8','9']]\n",
      " \n",
      "print \"value of board[0][0] : %c\" % (board[0][0])\n",
      "print \"value of board[0]: \", board[0][0]\n",
      "print \"value of **board: \", board[0][0]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "value of board[0][0] : 1\n",
        "value of board[0]:  1\n",
        "value of **board:  1\n"
       ]
      }
     ],
     "prompt_number": 10
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.8, page no. 281"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Getting values in a two-dimensional array\n",
      "\"\"\"\n",
      "\n",
      "board = [['1','2','3'],\n",
      "         ['4','5','6'],\n",
      "         ['7','8','9']]\n",
      "\n",
      "for i in range(3):\n",
      "    for j in range(3):\n",
      "        print \" board: \", board[i][j]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " board:  1\n",
        " board:  2\n",
        " board:  3\n",
        " board:  4\n",
        " board:  5\n",
        " board:  6\n",
        " board:  7\n",
        " board:  8\n",
        " board:  9\n"
       ]
      }
     ],
     "prompt_number": 11
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      " Program 7.9, page no. 283"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Multidimensional arrays and pointers\n",
      "\"\"\"\n",
      "\n",
      "board = [['1','2','3'],\n",
      "         ['4','5','6'],\n",
      "         ['7','8','9']]\n",
      "\n",
      "for i in range(3):\n",
      "    for j in range(3):\n",
      "        print \" board: \", board[i][j]"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " board:  1\n",
        " board:  2\n",
        " board:  3\n",
        " board:  4\n",
        " board:  5\n",
        " board:  6\n",
        " board:  7\n",
        " board:  8\n",
        " board:  9\n"
       ]
      }
     ],
     "prompt_number": 12
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.10, page no. 285"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Understand pointers to your hat size - if you dare\n",
      "\"\"\"\n",
      "\n",
      "size = [['6', '6', '6', '6', '7', '7', '7', '7', '7', '7', '7', '7'],\n",
      "        ['1', '5', '3', '7', ' ', '1', '1', '3', '1', '5', '3', '7'],\n",
      "        ['2', '8', '4', '8', ' ', '8', '4', '8', '2', '8', '4', '8']]\n",
      "headsize = [164, 166, 169, 172, 175, 178, 181, 184, 188, 191, 194, 197]\n",
      "hat_found = False\n",
      "print \"Enter the circumference of your head above your eyebrows in inches as a decimal value: \",\n",
      "cranium = float(raw_input())\n",
      "your_head = int(8.0*cranium)\n",
      "i = 0\n",
      "if(your_head == headsize[i]):\n",
      "    hat_found = True\n",
      "else:\n",
      "    for i in range(1, len(headsize)):\n",
      "        if(your_head > headsize[i - 1] and your_head <= headsize[i]):\n",
      "            hat_found = True\n",
      "            break\n",
      "if(hat_found):\n",
      "    print \"Your hat size is %c %c%c%c\" %(size[0][i], size[1][i], ' ' if (size[1][i]==' ') else '/', size[2][i])\n",
      "else:\n",
      "    if(your_head < headsize[0]):\n",
      "        print \"You are the proverbial pinhead. No hat for you I'm afraid.\"\n",
      "    else:\n",
      "        print \"You, in technical parlance, are a fathead, No hat for you, I'm afraid.\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Enter the circumference of your head above your eyebrows in inches as a decimal value: "
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "22.5\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " Your hat size is 7 1/4\n"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.11, page no. 290"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "A dynamic prime example\n",
      "note: program 7.12 will remain same\n",
      "\"\"\"\n",
      "\n",
      "pPrimes = []\n",
      "found = False\n",
      " \n",
      "print \"How many primes would you like - you'll get at least 4? \",\n",
      "total = int(raw_input())\n",
      "total = 4 if total < 4 else total\n",
      " \n",
      "pPrimes.append(2) # First prime\n",
      "pPrimes.append(3) # Second prime\n",
      "pPrimes.append(5) # Third prime\n",
      "count = 3\n",
      "trial = 5\n",
      " \n",
      "while(count < total):\n",
      "    trial += 2\n",
      "    for i in range(1, count):\n",
      "        if((trial % pPrimes[i]) == 0):\n",
      "            found = False\n",
      "            break\n",
      "        else:\n",
      "            found = True\n",
      "    if(found):\n",
      "        pPrimes.append(trial)\n",
      "        count += 1\n",
      "\n",
      "for i in range(total):\n",
      "    print \"\\t\", pPrimes[i],\n",
      "    if(not((i+1) % 5)):\n",
      "        print \"\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "How many primes would you like - you'll get at least 4? "
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "25\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " \t2 \t3 \t5 \t7 \t11 \n",
        "\t13 \t17 \t19 \t23 \t29 \n",
        "\t31 \t37 \t41 \t43 \t47 \n",
        "\t53 \t59 \t61 \t67 \t71 \n",
        "\t73 \t79 \t83 \t89 \t97 \n"
       ]
      }
     ],
     "prompt_number": 14
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.13, page no. 300"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Extending dynamically allocated memory for strings\n",
      "\"\"\"\n",
      "\n",
      "import sys\n",
      "\n",
      "print \"Enter text on an arbitrary number of lines (go on typing hit enter to terminate): \"\n",
      "print \"Should be less than 10000 characters: \"\n",
      "text = raw_input()\n",
      "\n",
      "if len(text) > 10000:\n",
      "    print \"Maximum length exceeded, terminating...\"\n",
      "    sys.exit()\n",
      "\n",
      "distinct_words = []\n",
      "word_occurrance = []\n",
      "list_text = text.split(\" \")\n",
      "for word in list_text:\n",
      "    if not word in distinct_words:\n",
      "        distinct_words.append(word)\n",
      "        word_occurrance.append(0)\n",
      "        \n",
      "for i in range(len(list_text)):\n",
      "    if list_text[i] in distinct_words:\n",
      "        index = distinct_words.index(list_text[i])\n",
      "        word_occurrance[index] += 1\n",
      "\n",
      "for i in range(len(distinct_words)):\n",
      "    if(i % 5 == 0):\n",
      "        print \"\\n\"\n",
      "    print distinct_words[i], \"\\t     \", word_occurrance[i],"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Enter text on an arbitrary number of lines (go on typing hit enter to terminate): \n",
        "Should be less than 10000 characters: \n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Peter Piper picked a peck of pickled pepper. A peck of pickled pepper Peter Piper picked. If Peter Piper picked a peck of pickled pepper, Where's the peck of pickled pepper Peter Piper picked?\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "\n",
        "Peter \t      4 Piper \t      4 picked \t      2 a \t      2 peck \t      4 \n",
        "\n",
        "of \t      4 pickled \t      4 pepper. \t      1 A \t      1 pepper \t      2 \n",
        "\n",
        "picked. \t      1 If \t      1 pepper, \t      1 Where's \t      1 the \t      1 \n",
        "\n",
        "picked? \t      1\n"
       ]
      }
     ],
     "prompt_number": 15
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.14, page no. 306"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Using array notation with pointers to sort strings\n",
      "\"\"\"\n",
      "\n",
      "print \"Enter strings to be sorted, separated by '.' Press Enter to end: \"\n",
      "text = raw_input()\n",
      "\n",
      "dot_separated = text.split('.')\n",
      "text_sorted = sorted(dot_separated)\n",
      "\n",
      "for str in text_sorted:\n",
      "    print str"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Enter strings to be sorted, separated by '.' Press Enter to end: \n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Many a mickle makes a muckle. A fool and your money are soon partners. Every dog has his day. Do unto others before they do it to you. A nod is as good as a wink to a blind horse. The bigger they are, the harder they hit. Least said, soonest mended.\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        " A fool and your money are soon partners\n",
        " A nod is as good as a wink to a blind horse\n",
        " Do unto others before they do it to you\n",
        " Every dog has his day\n",
        " Least said, soonest mended\n",
        " The bigger they are, the harder they hit\n",
        "Many a mickle makes a muckle\n"
       ]
      }
     ],
     "prompt_number": 16
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 7.15, page no. 316"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "An improved calculator\n",
      "\"\"\"\n",
      "\n",
      "print \"To use this calculator, enter any expression with or without spaces.\"\n",
      "print \"An expression may include the operators\"\n",
      "print \" +, -, *, /, %, or **(raise to a power).\"\n",
      "print \"Use = at the beginning of a line to operate on \"\n",
      "print \"the result of the previous calculation.\"\n",
      "print \"Enter quit to stop the calculator.\"\n",
      "\n",
      "result = 0\n",
      "while True:\n",
      "    e = raw_input()\n",
      "    if e == 'quit':\n",
      "        break\n",
      "    else:\n",
      "        try:\n",
      "            result = eval(str(result) + e)\n",
      "            print \"= \",result\n",
      "        except ZeroDivisionError:\n",
      "            print \"Division by zero\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "To use this calculator, enter any expression with or without spaces.\n",
        "An expression may include the operators\n",
        " +, -, *, /, %, or **(raise to a power).\n",
        "Use = at the beginning of a line to operate on \n",
        "the result of the previous calculation.\n",
        "Enter quit to stop the calculator.\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "7/8\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "=  0\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "/0\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Division by zero\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "+3\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "=  3\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "/2\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "=  1\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "**5\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "=  1\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "+8\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "=  9\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "*2\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "=  18\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "quit\n"
       ]
      }
     ],
     "prompt_number": 2
    }
   ],
   "metadata": {}
  }
 ]
}