practice-exercise-07-solution.ipynb

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   "source": [
    "# Practice Exercise - 07 - Solution"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 1:\n",
    "\n",
    "We have defined a variable x equals 2. Then we have the if-else condition, which checks if x is equal to 2 or not. But we get an error in the output. Decode the error and rectify the program to get the expected output.\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Exact match!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Exact match!\n"
     ]
    }
   ],
   "source": [
    "x = 2\n",
    "\n",
    "if x == 2:\n",
    "    print('Exact match!')\n",
    "else:\n",
    "    print('Not a match!')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Explanation:\n",
    "\n",
    "When comparing, we need to use the equality operator(==), not the assignment operator(=)."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 2:\n",
    "\n",
    "There is a message given below. When we try to print the message, we are getting a syntax error. Look at the error and rectify it.\n",
    "\n",
    "<br>msg = 'Don't run in the park.'\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Don't run in the park."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Don't run in the park.\n"
     ]
    }
   ],
   "source": [
    "msg = 'Don\\'t run in the park.'\n",
    "\n",
    "print(msg)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 3:\n",
    "\n",
    "We have a program given below that generates an *AttributeError* exception. Make changes in the program to handle this exception and print the message *'An error occured.'*\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "An error occurred."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "An error occurred.\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    num = (5, 7, 9, 11)\n",
    "    num.append(13)\n",
    "except AttributeError:\n",
    "    print('An error occurred.')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 4:\n",
    "\n",
    "We have a function given below which prints an element from the list. But what if the user calls an invalid index? So, I want you to re-write the following function using the try-except block to handle the *IndexError* exception.\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Invalid index, try again."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Invalid index, try again.\n"
     ]
    }
   ],
   "source": [
    "def getData(data, index):\n",
    "    try:\n",
    "        return data[index]\n",
    "    except IndexError:\n",
    "        print('Invalid index, try again.')\n",
    "\n",
    "names = ['Alpha', 'Victor', 'Charles']\n",
    "\n",
    "getData(names, 5)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 5:\n",
    "\n",
    "We have a function given below that adds elements of two lists. However, I can think of two exceptions that can occur in this program. \n",
    "\n",
    "1. The index entered by the user during the function call may be out of bound.\n",
    "2. The list entered by the user can consist of int objects, str objects, or even a combination of both. And what if we try to add an int object and an str object?\n",
    "\n",
    "Re-write this program to handle the two exceptions mentioned above.\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Invalid index, try again."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Invalid index, try again.\n"
     ]
    }
   ],
   "source": [
    "def add_elements(data_1, data_2, index):\n",
    "    try:\n",
    "        return data_1[index] + data_2[index]\n",
    "    except IndexError:\n",
    "        print('Invalid index, try again.')\n",
    "        return\n",
    "    except TypeError:\n",
    "        print('Invalid addition of objects, check the lists.')\n",
    "        return\n",
    "\n",
    "numList_1 = [1, 5, 9, 15]\n",
    "numList_2 = [2, 7, 11, 18]\n",
    "\n",
    "add_elements(numList_1, numList_2, 5)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 6:\n",
    "\n",
    "Write a Python program to find the day of the week for the date given below. Also, we don't know what errors we might encounter while executing the program. So, wrap the code inside a try-except block and handle the exceptions by printing the message *'Oops! An error occurred.'*\n",
    "\n",
    "given_date = datetime(2010, 6, 12)\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Saturday"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Saturday\n"
     ]
    }
   ],
   "source": [
    "from datetime import datetime\n",
    "try:\n",
    "    given_date = datetime(2010, 6, 12)\n",
    "    print(given_date.strftime('%A'))    \n",
    "except:\n",
    "    print('Oops! An error occured.')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 7:\n",
    "\n",
    "Write a function to reverse a string if it's length is an even number. I think of the *TypeError* exception if a numeric value is passed inside the function call. But there might be other exceptions too that can occur while executing the program. \n",
    "<br>So, wrap the function around a try-except block and handle the *TypeError* exception with the message *'Check the string.'* For all other exceptions, print the message *'Something went wrong.'*\n",
    "\n",
    "*Input String = 'Python'*\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "nohtyP"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "nohtyP\n"
     ]
    }
   ],
   "source": [
    "def reverse_string(text):\n",
    "    try:\n",
    "        if len(text) % 2 == 0:\n",
    "            return ''.join(reversed(text))            \n",
    "        else:\n",
    "            print('String\\'s length is an odd number. Could not reverse.')\n",
    "            return\n",
    "    except TypeError:\n",
    "        print('Check the string.')  \n",
    "        return\n",
    "    except:\n",
    "        print('Something went wrong.')  \n",
    "        return\n",
    "    \n",
    "print(reverse_string('Python'))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 8:\n",
    "\n",
    "Write a function to extract the first ten letters of a string passed as an argument. But if the string is less than ten characters long, raise a *ValueError* and handle it using the message *'Oops! Too short string.'*\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Oops! Too short string."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Oops! Too short string.\n"
     ]
    }
   ],
   "source": [
    "def extract_five_letters(text):\n",
    "    try:\n",
    "        if len(text) > 10:\n",
    "            return text[:10]  \n",
    "        else:\n",
    "            raise ValueError\n",
    "    except:\n",
    "        print('Oops! Too short string.')\n",
    "        \n",
    "extract_five_letters('Python')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 9:\n",
    "\n",
    "Write a program to square the number entered by the user. But what if the user enters a string or an alphanumeric value, or if some other unexpected exceptions occur. So, wrap the program inside the try-except block to handle the exceptions, and the program should run until the user enters a numeric value.\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "*Enter a number*: aa\n",
    "<br>Enter a valid input.\n",
    "<br>*Enter a number*: 5\n",
    "<br>25"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Enter a number: aa\n",
      "Enter a valid input.\n",
      "Enter a number: 5\n",
      "25\n"
     ]
    }
   ],
   "source": [
    "while True:\n",
    "    try:\n",
    "        n = int(input('Enter a number: ')) \n",
    "        print(n**2) \n",
    "        break\n",
    "    except:\n",
    "        print('Enter a valid input.')   "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Question 10:\n",
    "\n",
    "Write a program to process the results of the user. The program should consist of a user-defined exception class *'InvalidNumError'* to raise an error if the marks entered by the user is less than 0 or greater than 100. Otherwise, print the message *'Results processing.'*\n",
    "\n",
    "#### Expected Output:\n",
    "\n",
    "Results processing.\n",
    "<br>Error! Try again."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Results processing.\n",
      "Error! Try again.\n"
     ]
    }
   ],
   "source": [
    "class InvalidNumError(Exception):\n",
    "    pass\n",
    "\n",
    "def marks_check(marks):\n",
    "    try:\n",
    "        if int(marks) < 0:\n",
    "            raise InvalidNumError\n",
    "        elif int(marks) > 100:\n",
    "            raise InvalidNumError\n",
    "        else:\n",
    "            print('Results processing.')\n",
    "    except InvalidNumError:\n",
    "        print('Error! Try again.')\n",
    "    \n",
    "marks_check(50)\n",
    "marks_check(105) "
   ]
  }
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