{
 "metadata": {
  "name": "Chapter 15"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": "Chapter 15: Debugging and optimization"
    },
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": "Example 15.1, Page number: 275"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "# Example 15.1.py\n# A database program to look up names in a hardcoded list\n\n\n# Function declaration\ndef lookup (name) :\n   lists = ['John', 'Jim', 'Jane', 'Clyde']\n   result = 0\n\n   for index in range (0, 4) :\n      if (lists[index] == name) :\n         result = 1\n         break\n   \n   return result\n\n# Calculation and result\nname = 'John'\n\nif (lookup (name)) :\n   print ('%s is in the list\\n' % name)\nelse :\n   print ('%s is not in the list\\n' % name)",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "John is in the list\n\n"
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": "Example 15.6, Page number: 288"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "# Example 15.6.py\n# To count the number of 3's and 7's in an array\n\n\n# Variable and function declaration\nseven_count = 0\nthree_count = 0\ndata = []\n\ndef get_data (data) :\n   for i in range (0, 5) :\n      x = 3\n      data.append(int(x))\n   print (data)\n\n# Calculation\nget_data (data)\nfor index in range (0, 5) :\n   if data[index] == 3 :\n      three_count += 1\n\n   if data[index] == 7 :\n      seven_count += 1\n\n# Result\nprint ('Threes %d Sevens %d' % (three_count, seven_count))",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "[3, 3, 3, 3, 3]\nThrees 5 Sevens 0\n"
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": "Example 15.7, Page number: 292"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "# Example 15.7.py\n# To perform binary search on a number in a file 'numbers.dat'\n\n\n# Variable declaration\nimport sys\nimport os\nin_file = open ('numbers.dat', 'r')\n\ndata = []\nmax_count = 0\n \n# Calculation and result\nif not os.path.exists ('numbers.dat') :\n   print ('Error:Unable to open numbers.dat\\n')\n   sys.exit(1)\n\nfor line in in_file :\n   data.append(line)\n   max_count += 1\n\nwhile (1) :\n   search = 6\n   \n   if (search == -1) :\n      break\n\n   low = 0\n   high = max_count\n\n   while (1) :\n      mid = (low + high) / 2\n      middle = int (mid)      \n\n      if (int (data[middle]) == search) :\n         print ('Found at index %d\\n' % (middle + 1))\n         break\n\n      if (low == high) :\n         print ('Not found\\n')\n         break\n\n      if (int (data[middle]) < search) :\n         low = middle\n      else :\n         high = middle      \n\nin_file.close()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "IOError",
       "evalue": "[Errno 2] No such file or directory: 'numbers.dat'",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mIOError\u001b[0m                                   Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-5-ce867c3a4ec5>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      6\u001b[0m \u001b[1;32mimport\u001b[0m \u001b[0msys\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      7\u001b[0m \u001b[1;32mimport\u001b[0m \u001b[0mos\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 8\u001b[1;33m \u001b[0min_file\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mopen\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'numbers.dat'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'r'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      9\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     10\u001b[0m \u001b[0mdata\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;33m[\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mIOError\u001b[0m: [Errno 2] No such file or directory: 'numbers.dat'"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": "Example 15.8, Page number: 300"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "# Example 15.8.py\n# To perform binary search on a number in a file 'numbers.dat'\n\n\n# Variable declaration\nimport sys\nimport os\nin_file = open ('numbers.dat', 'r')\n\ndata = []\nmax_count = 0\n \n# Calculation and result\nif not os.path.exists ('numbers.dat') :\n   print ('Error:Unable to open numbers.dat\\n')\n   sys.exit(1)\n\nfor line in in_file :\n   data.append(line)\n   max_count += 1\n\nwhile (1) :\n   search = 14\n   \n   if (search == -1) :\n      break\n\n   low = 0\n   high = max_count\n\n   while (1) :\n      mid = (low + high) / 2\n      middle = int (mid)      \n\n      if (int (data[middle]) == search) :\n         print ('Found at index %d\\n' % (middle + 1))\n         break\n\n      if (low == high) :\n         print ('Not found\\n')\n         break\n\n      if (int (data[middle]) < search) :\n         low = middle\n      else :\n         high = middle      \n\nin_file.close()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "IOError",
       "evalue": "[Errno 2] No such file or directory: 'numbers.dat'",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mIOError\u001b[0m                                   Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-6-8cd3b79f72a3>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m      6\u001b[0m \u001b[1;32mimport\u001b[0m \u001b[0msys\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      7\u001b[0m \u001b[1;32mimport\u001b[0m \u001b[0mos\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 8\u001b[1;33m \u001b[0min_file\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mopen\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'numbers.dat'\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;34m'r'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      9\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     10\u001b[0m \u001b[0mdata\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;33m[\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mIOError\u001b[0m: [Errno 2] No such file or directory: 'numbers.dat'"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": "Example 15.10, Page number: 304"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "# Example 15.10.py\n# To illustrate divide by zero error\n\n\n# Variable declaration\ni = 1\nj = 0\n\n# Calculation and result\nprint ('Starting\\n')\nprint ('Before divide...')\ni = i / j\nprint ('After\\n')",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "ename": "ZeroDivisionError",
       "evalue": "integer division or modulo by zero",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mZeroDivisionError\u001b[0m                         Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-7-289ff2a55d4d>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m     10\u001b[0m \u001b[1;32mprint\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'Starting\\n'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     11\u001b[0m \u001b[1;32mprint\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'Before divide...'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m---> 12\u001b[1;33m \u001b[0mi\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mi\u001b[0m \u001b[1;33m/\u001b[0m \u001b[0mj\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m     13\u001b[0m \u001b[1;32mprint\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'After\\n'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mZeroDivisionError\u001b[0m: integer division or modulo by zero"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Starting\n\nBefore divide...\n"
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "heading",
     "level": 3,
     "metadata": {},
     "source": "Example 15.11, Page number: 304"
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "# Example 15.11.py\n# To illustrate divide by zero error with flush() function\n\n\n# Variable declaration\nimport sys\ni = 1\nj = 0\n\n# Calculation and result\nprint ('Starting\\n')\nsys.stdout.flush()\nprint ('Before divide...')\nsys.stdout.flush()\ni = i / j\nprint ('After\\n')\nsys.stdout.flush()",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Starting\n\n"
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "Before divide...\n"
      },
      {
       "ename": "ZeroDivisionError",
       "evalue": "integer division or modulo by zero",
       "output_type": "pyerr",
       "traceback": [
        "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[1;31mZeroDivisionError\u001b[0m                         Traceback (most recent call last)",
        "\u001b[1;32m<ipython-input-8-eedd2fda3e82>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[0;32m     13\u001b[0m \u001b[1;32mprint\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'Before divide...'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     14\u001b[0m \u001b[0msys\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mstdout\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mflush\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m---> 15\u001b[1;33m \u001b[0mi\u001b[0m \u001b[1;33m=\u001b[0m \u001b[0mi\u001b[0m \u001b[1;33m/\u001b[0m \u001b[0mj\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m     16\u001b[0m \u001b[1;32mprint\u001b[0m \u001b[1;33m(\u001b[0m\u001b[1;34m'After\\n'\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m     17\u001b[0m \u001b[0msys\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mstdout\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mflush\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
        "\u001b[1;31mZeroDivisionError\u001b[0m: integer division or modulo by zero"
       ]
      }
     ],
     "prompt_number": 8
    }
   ],
   "metadata": {}
  }
 ]
}