path: root/Beginning_C_By_Ivon_Horton/chapter12.ipynb

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   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Chapter 12: Working with Files"
     ]
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.1, page no. 498"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Writing a file a character at a time\n",
      "\"\"\"\n",
      "\n",
      "import sys\n",
      "\n",
      "\n",
      "mystr = []\n",
      "\n",
      "print \"Enter an interesting string of up to 80 characters: \",\n",
      "mystr = raw_input()\n",
      "\n",
      "try:\n",
      "    fp = open(\"myfile.txt\", \"w\")\n",
      "except:\n",
      "    print \"error opening the file...\"\n",
      "    sys.exit()\n",
      "\n",
      "for i in range(len(mystr)-1, -1, -1):\n",
      "    fp.write(mystr[i])\n",
      "\n",
      "fp.close()\n",
      "\n",
      "try:\n",
      "    fp = open(\"myfile.txt\", \"r\")\n",
      "except:\n",
      "    print \"error opening the file...\"\n",
      "\n",
      "print \"the data read from the file is: \"\n",
      "while(True):\n",
      "    c = fp.read(1)\n",
      "    if not c:\n",
      "        break\n",
      "    print c,\n",
      "fp.close()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Enter an interesting string of up to 80 characters: "
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Too many cooks spoil the broth.\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " the data read from the file is: \n",
        ". h t o r b   e h t   l i o p s   s k o o c   y n a m   o o T\n"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.2, page no. 502"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "As the saying goes. . .it comes back!\n",
      "\"\"\"\n",
      "\n",
      "proverbs = [\"Many a mickle makes a muckle.\\n\",\n",
      "            \"Too many cooks spoil the broth.\\n\",\n",
      "            \"He who laughs last didn't get the joke in the first place.\\n\"]\n",
      " \n",
      "more = []\n",
      "\n",
      "try:\n",
      "    fp = open(\"myfile.txt\", \"w\") \n",
      "except:\n",
      "    print \"error opening the file...\"\n",
      "for proverb in proverbs:\n",
      "    fp.write(proverb)\n",
      "fp.close()\n",
      " \n",
      "fp = open(\"myfile.txt\", \"a\")\n",
      " \n",
      "print \"Enter proverbs of up to 80 characters (separated by '.') or press Enter to end:\\n\",\n",
      "string = raw_input().split('.')\n",
      "\n",
      "\n",
      "for str in string:\n",
      "    fp.write(str+\"\\n\")\n",
      "fp.close()\n",
      "\n",
      "fp = open(\"myfile.txt\", \"r\")\n",
      "print \"The proverbs in the file are: \\n\"\n",
      "while(True):\n",
      "    line = fp.readline()\n",
      "    if not line:\n",
      "        break\n",
      "    print line\n",
      "fp.close()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Enter proverbs of up to 80 characters (separated by '.') or press Enter to end:\n"
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Every dog has his day. Least said, soonest mended. A stitch in time saves nine. Waste not, want not.\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "The proverbs in the file are: \n",
        "\n",
        "Many a mickle makes a muckle.\n",
        "\n",
        "Too many cooks spoil the broth.\n",
        "\n",
        "He who laughs last didn't get the joke in the first place.\n",
        "\n",
        "Every dog has his day\n",
        "\n",
        " Least said, soonest mended\n",
        "\n",
        " A stitch in time saves nine\n",
        "\n",
        " Waste not, want not\n",
        "\n",
        "\n",
        "\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.3, page no. 507"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\"\"\"\n",
      "Messing about with formatted file I/O\n",
      "\"\"\"\n",
      "\n",
      "import sys\n",
      "\n",
      "num1 = 234567\n",
      "num2 = 345123\n",
      "num3 = 789234\n",
      "\n",
      "ival = []\n",
      "\n",
      "try:\n",
      "    fp = open(\"myfile.txt\", \"w\")\n",
      "except:\n",
      "    print \"Error opening file for writing. Program terminated.\\n\"\n",
      "    sys.exit()\n",
      "\n",
      "fp.write(\"%6d %6d %6d\" %(num1, num2, num3))\n",
      "fp.close()\n",
      "print \"%6ld %6ld %6ld\" %(num1, num2, num3)\n",
      "\n",
      "try: \n",
      "    fp = open(\"myfile.txt\", \"r\")\n",
      "except:\n",
      "    print \"Error opening file for reading. Program terminated.\\n\"\n",
      "    sys.exit()\n",
      "\n",
      "line = fp.readline()\n",
      "line_split = line.split(\" \")\n",
      "num4 = int(line_split[0])\n",
      "num5 = int(line_split[1])\n",
      "num6 = int(line_split[2])\n",
      "print \"%6ld %6ld %6ld \" %(num4, num5, num6)\n",
      "fp.close\n",
      "\n",
      "fp = open(\"myfile.txt\", \"r\")\n",
      "line = fp.readline()\n",
      "line_join = \"\".join(line_split)\n",
      "ival.append(int(line_join[0:2]))\n",
      "ival.append(int(line_join[2:5]))\n",
      "ival.append(int(line_join[5:8]))\n",
      "ival.append(int(line_join[8:11]))\n",
      "ival.append(int(line_join[11:13]))\n",
      "ival.append(int(line_join[13:15]))\n",
      "fnum = (float(line_join[15:]))\n",
      "\n",
      "for i in range(len(ival)):\n",
      "    print \"%sival[%d] = %d\" %((\"\\n\\t\" if i == 4 else \"\\t\"), i, ival[i]),\n",
      "print \"\\nfnum = %f \" %fnum"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "234567 345123 789234\n",
        "234567 345123 789234 \n",
        "\tival[0] = 23 \tival[1] = 456 \tival[2] = 734 \tival[3] = 512 \n",
        "\tival[4] = 37 \tival[5] = 89 \n",
        "fnum = 234.000000 \n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.4, page no. 514"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Program 12.4, page no. 514\n",
      "\n",
      "\"\"\"\n",
      "A prime example using binary files\n",
      "\"\"\"\n",
      "\n",
      "import math\n",
      "import sys\n",
      "\n",
      "MEM_PRIMES = 10\n",
      "PER_LINE = 8\n",
      "filename = \"myfile.bin\"\n",
      "fp = None\n",
      "primes = [2, 3, 5]\n",
      "count = 3\n",
      "\n",
      "def check(buff, count, n):\n",
      "    root_N = (1.0 + math.sqrt(n))\n",
      "    for i in range(0, count):\n",
      "        if(n % buff[i] == 0):\n",
      "            return 0\n",
      "        if(buff[i] > root_N):\n",
      "            return 1\n",
      "    return -1\n",
      "\n",
      "def list_array():\n",
      "    global primes\n",
      "    global count\n",
      "    for j in range(count):\n",
      "        print \"%10lu\" %primes[j]\n",
      "        if(((j + 1) % PER_LINE) == 0):\n",
      "            print \"\\n\"\n",
      "    \n",
      "def list_primes():\n",
      "    global fp\n",
      "    global filename\n",
      "    global count\n",
      "    global primes\n",
      "    if(fp):\n",
      "        try:\n",
      "            fp = open(filename, \"rb\")\n",
      "        except:\n",
      "            print \"Unable to open %s to read primes for output \" %filename\n",
      "            sys,exit()\n",
      "        while(True):\n",
      "            line = fp.readline()\n",
      "            if line:\n",
      "                list_array()\n",
      "        print \"\\n\"\n",
      "        fp.close()\n",
      "    else:\n",
      "        list_array()\n",
      "\n",
      "def write_file():\n",
      "    global fp\n",
      "    global filename\n",
      "    global count\n",
      "    global primes\n",
      "    try:\n",
      "        fp = open(filename, \"ab\")\n",
      "    except:\n",
      "        print \"Unable to open %s to append\\n\" %filename\n",
      "        sys.exit()\n",
      "    for prime in primes:\n",
      "        fp.write(prime+\" \")\n",
      "    fp.close\n",
      "    count = 0\n",
      "\n",
      "def is_prime(n):\n",
      "    global filename\n",
      "    global fp\n",
      "    global primes\n",
      "    global count \n",
      "    buff = []\n",
      "    count = 0\n",
      "    k = 0\n",
      "    if(fp):\n",
      "        try:\n",
      "            fp = open(filename, \"rb\")\n",
      "        except:\n",
      "            print \"Unable to open %s to read. \" %g.filename\n",
      "            sys.exit()\n",
      "        while(True):\n",
      "            line = fp.readline()\n",
      "            if line:\n",
      "                nums = line.split(\" \")\n",
      "                for num in nums:\n",
      "                    buff.append(int(num))\n",
      "                k = check(buff, count, n)\n",
      "                if(k == 1):\n",
      "                    fp.close()\n",
      "                    return True\n",
      "            else:   \n",
      "                break\n",
      "        fp.close()\n",
      "    return 1 == check(primes, count, n)\n",
      "\n",
      "trial = primes[count - 1]\n",
      "num_primes = 3\n",
      "\n",
      "print \"How many primes would you like? \",\n",
      "total = int(raw_input())\n",
      "total = 4 if total < 4 else total\n",
      "print total\n",
      "while(num_primes < total):\n",
      "    trial += 2\n",
      "    if(is_prime(trial)):\n",
      "        primes.append(trial)\n",
      "        count += 1\n",
      "        num_primes += 1\n",
      "        if(count == MEM_PRIMES):\n",
      "            write_file()\n",
      "\n",
      "if(fp and count > 0):\n",
      "    write_file()\n",
      "list_primes()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 11
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.5, page no. 523"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Program 12.5, page no. 523\n",
      "\n",
      "\"\"\"\n",
      "Investigating the family.\n",
      "\"\"\"\n",
      "\n",
      "class Date:\n",
      "    day = 0\n",
      "    month = 0\n",
      "    year = 0\n",
      " \n",
      "class Family:\n",
      "    dob = Date()\n",
      "    name = \"\"\n",
      "    pa_name = \"\"\n",
      "    ma_name = \"\"\n",
      "\n",
      "members = []\n",
      "\n",
      "def get_person():\n",
      "    while(True):\n",
      "        temp = Family()\n",
      "        print \"Enter the name of the person: \",\n",
      "        temp.name = raw_input()\n",
      "        print \"Enter %s's date of birth (day month year): \" %temp.name\n",
      "        temp.dob.day = int(raw_input(\"Day: \"))\n",
      "        temp.dob.month = int(raw_input(\"Month: \"))\n",
      "        temp.dob.year = int(raw_input(\"Year: \"))\n",
      "        print \"Who is %s's father? \" %temp.name,\n",
      "        temp.pa_name = raw_input()\n",
      "        print \"Who is %s's mother? \" %temp.name,\n",
      "        temp.ma_name = raw_input()\n",
      "        print \"\\nDo you want to enter details of a person (Y or N)? \",\n",
      "        more = raw_input()\n",
      "        members.append(temp)\n",
      "        if(more.lower() == 'n'):\n",
      "            return\n",
      "\n",
      "def show_person_data():\n",
      "    fp = open(\"myfile.bin\", \"rb\")\n",
      "    count = 0\n",
      "    while(True):\n",
      "        line = fp.readline()\n",
      "        if line:\n",
      "            member_data = line.split(\",\")\n",
      "            print \"%s's father is %s, and mother is %s.\" %(member_data[0],member_data[4], member_data[5])\n",
      "            found_relative, relative_info = get_parent_dob(members[count])\n",
      "            if found_relative:\n",
      "                print relative_info\n",
      "            else:\n",
      "                print \"No info on parents available\"\n",
      "        else:\n",
      "            break\n",
      "    fp.close()\n",
      "\n",
      "def get_parent_dob(member):\n",
      "    parent_info = \"\"\n",
      "    found_relative = False\n",
      "    for parent in members:\n",
      "        if parent.name == member.pa_name:\n",
      "            parent_info = parent_info+\"Pa was born on %d %d %d\" %(parent.dob.day, parent.dob.month, parent.dob.year)\n",
      "            found_relative = True\n",
      "        elif parent.name == member.ma_name:\n",
      "            parent_info = parent_info+\" Ma was born on %d %d %d\" %(parent.dob.day, parent.dob.month, parent.dob.year)\n",
      "            found_relative = True\n",
      "    return found_relative, parent_info\n",
      "\n",
      "\n",
      "print \"Do you want to add details of a person ? (Y/N): \",\n",
      "more = raw_input()\n",
      "if more.lower() == 'n':\n",
      "    import sys\n",
      "    sys.exit()\n",
      "\n",
      "get_person()\n",
      "fp = open(\"myfile.bin\", \"wb\")\n",
      "for member in members:\n",
      "    line = member.name+\",\"+str(member.dob.day)+\",\"+str(member.dob.month)+\",\"+str(member.dob.year)   +\",\"+member.pa_name+\",\"+member.ma_name\n",
      "    fp.write(line)\n",
      "    fp.write(\",\\n\")\n",
      "fp.close()\n",
      "show_person_data()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 11
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.6, page no. 531"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Program 12.6, page no. 531\n",
      "\n",
      "\"\"\"\n",
      "Writing a binary file with an update mode\n",
      "\"\"\"\n",
      "\n",
      "MAXLEN = 50\n",
      "\n",
      "def listfile():\n",
      "    fp = open(\"mypeople.bin\", \"rb\")\n",
      "    print \"The folks recorded in the mypeople.bin file are: \"\n",
      "    while(True):\n",
      "        line = fp.readline()\n",
      "        if line:\n",
      "            print line.split(\",\")[0], \"\\t\\t\\t\\t\\t\", line.split(\",\")[1]\n",
      "        else:\n",
      "            break\n",
      "    fp.close()\n",
      "\n",
      "answer = 'y'\n",
      "fp = open(\"mypeople.bin\", \"wb\")\n",
      "while(answer.lower() == 'y'):\n",
      "    print \"Enter a name less than %d characters: \" %MAXLEN,\n",
      "    name = raw_input()\n",
      "    print \"Enter the age of %s: \" %name,\n",
      "    age = int(raw_input())\n",
      "    length = len(name)\n",
      "    line = name+\",\"+str(age)\n",
      "    fp.write(line)\n",
      "    fp.write(\" \\n\")\n",
      "    print \"Do you want to enter another(y or n)? \",\n",
      "    answer = raw_input()\n",
      "fp.close()\n",
      "listfile()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 11
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.7, page no. 545"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# Program 12.7, page no. 545\n",
      "\n",
      "\"\"\"\n",
      "Writing, reading and updating a binary file\n",
      "\"\"\"\n",
      "\n",
      "class Record:\n",
      "    name = \"\"\n",
      "    age = 0\n",
      "\n",
      "records = []\n",
      "\n",
      "def write_file(mode):\n",
      "    global filename\n",
      "    fp = open(filename, mode)\n",
      "    more = 'y'\n",
      "    while(more == 'y'):\n",
      "        print \"Enter name less than 30 characters: \",\n",
      "        name = raw_input()\n",
      "        name = \"%30s\" %name\n",
      "        print \"Enter age of \", name\n",
      "        age = raw_input()\n",
      "        age = \"%3s\" %age\n",
      "        line = name+\",\"+age\n",
      "        fp.write(line)\n",
      "        fp.write(\" \\n\")\n",
      "        print \"Do you want to enter another (y/n)? \",\n",
      "        more = raw_input()\n",
      "    fp.close()\n",
      "    return\n",
      "\n",
      "def list_file():\n",
      "    global filename\n",
      "    fp = open(filename, \"rb\")\n",
      "    print \"The folks recorded in the mypeople.bin file are: \"\n",
      "    while(True):\n",
      "        line = fp.readline()\n",
      "        if line:\n",
      "            line_split = line.split(\",\")\n",
      "            print line_split[0].strip(), \"\\t\\t\\t\\t\\t\", line_split[1]\n",
      "        else:\n",
      "            break\n",
      "    fp.close()\n",
      "\n",
      "def remove(fname):\n",
      "    import os\n",
      "    os.remove(fname)\n",
      "\n",
      "def update_file():\n",
      "    global filename\n",
      "    new_record = Record()\n",
      "    fp = open(filename, \"rb+\")\n",
      "    print \"Enter name to be updated: \",\n",
      "    update_name = raw_input()\n",
      "    update_name = \"%30s\"%update_name\n",
      "    while(True):\n",
      "        old_pos = fp.tell()\n",
      "        old_line = fp.readline()\n",
      "        if old_line:\n",
      "            if old_line.split(\",\")[0] == update_name:\n",
      "                print \"You can now enter new name and age for \", update_name\n",
      "                print \"Enter name less than 30 charactesrs: \",\n",
      "                new_name = raw_input()\n",
      "                new_name = \"%30s\"%new_name\n",
      "                print \"Enter age for \", new_name\n",
      "                new_age = raw_input()\n",
      "                new_age = \"%3s\"%new_age\n",
      "                pos = fp.tell()\n",
      "                fp.seek(old_pos)\n",
      "                new_line = new_name+\",\"+new_age+\" \\n\"\n",
      "                new_line = old_line.replace(old_line, new_line)\n",
      "                fp.write(new_line)\n",
      "        else:\n",
      "            break\n",
      "    fp.close()\n",
      "    \n",
      "filename = \"my-people.bin\"\n",
      "answer = 'q'\n",
      "while(True):\n",
      "    print \"Choose from the following options: \"\n",
      "    print \"To list the file contents enter L\"\n",
      "    print \"To create a new file enter C \"\n",
      "    print \"To add new records enter A\"\n",
      "    print \"To update existing records enter U\"\n",
      "    print \"To delete the file enter D\"\n",
      "    print \"To end the program enter Q: \",\n",
      "    answer = raw_input()\n",
      "    if answer.upper() == 'L':\n",
      "        list_file()\n",
      "    elif answer.upper() == 'C':\n",
      "        write_file(\"wb+\")\n",
      "        print \"File creation complete.\"\n",
      "    elif answer.upper() == 'A':\n",
      "        write_file(\"ab+\");\n",
      "        print \"File append complete.\"\n",
      "    elif answer.upper() == 'U':\n",
      "        update_file()\n",
      "    elif answer.upper() == 'D':\n",
      "        print \"Are you sure you want to delete %s (y or n)? \",\n",
      "        confirm_delete = raw_input()\n",
      "        if(confirm_delete.lower() == 'y'):\n",
      "            remove(filename)\n",
      "    elif answer.upper() == 'Q':\n",
      "        print \"Ending the program. \"\n",
      "        import sys\n",
      "        sys.exit()\n",
      "    else:\n",
      "        print \"Invalid selection. Try again.\""
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 11
    },
    {
     "cell_type": "heading",
     "level": 2,
     "metadata": {},
     "source": [
      "Program 12.8, page no. 551"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import binascii\n",
      "\n",
      "print \"Enter filename: \",\n",
      "filename = raw_input()\n",
      "\n",
      "f = open(filename, \"r\")\n",
      "\n",
      "for line in f.readlines():\n",
      "    print (binascii.hexlify(line)),\n",
      "    print \" | \", line\n",
      "\n",
      "f.close()"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Enter filename: "
       ]
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "myfile.txt\n"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        " 2e68746f726220656874206c696f707320736b6f6f6320796e616d206f6f54  |  .htorb eht liops skooc ynam ooT\n"
       ]
      }
     ],
     "prompt_number": 14
    }
   ],
   "metadata": {}
  }
 ]
}