CHAPTER 6 exercises.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 1: Write a while loop that starts at the last character in the string and\n",
    "works its way backwards to the first character in the string, printing each letter on\n",
    "a separate line, except backwards.**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Enter a word:banana\n",
      "a\n",
      "n\n",
      "a\n",
      "n\n",
      "a\n",
      "b\n"
     ]
    }
   ],
   "source": [
    "word = str(input ('Enter a word:'))\n",
    "index = len(word)-1\n",
    "while index > -1:\n",
    "    print (word[index])\n",
    "    index = index-1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 2: Given that fruit is a string, what does fruit[:] mean?**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'pineapple'"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fruit = 'pineapple'\n",
    "fruit[:]  # prints the fruit"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 3:\n",
    "Encapsulate this code in a function named count, and generalize it so that it\n",
    "accepts the string and the letter as arguments.**"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "word = 'banana'\n",
    "count = 0\n",
    "for letter in word:\n",
    "    if letter == 'a':\n",
    "        count = count + 1\n",
    "    print(count)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Enter a word: hannah baker\n",
      "Enter letter to be couted: a\n",
      "3\n"
     ]
    }
   ],
   "source": [
    "def count(word,fletter):\n",
    "    count = 0\n",
    "    for letter in word:\n",
    "        if letter == fletter:\n",
    "            count = count + 1\n",
    "    print(count)\n",
    "\n",
    "word = input('Enter a word: ')\n",
    "fletter = input('Enter letter to be couted: ')\n",
    "count(word,fletter)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 4:\n",
    "There is a string method called count that is similar to the function\n",
    "in the previous exercise. Read the documentation of this method at\n",
    "https://docs.python.org/3.5/library/stdtypes.html#string-methods and write an\n",
    "invocation that counts the number of times the letter a occurs in “banana”.**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "3\n"
     ]
    }
   ],
   "source": [
    "string = 'banana'\n",
    "letter = 'a'\n",
    "print(string.count(letter))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2\n"
     ]
    }
   ],
   "source": [
    "print(string.count(letter,2,6))\n",
    "# Return the number of non-overlapping occurrences of substring letter in the range [start, end].\n",
    "# Optional arguments start and end are interpreted as in slice notation."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 5: Take the following Python code that stores a string:‘**\n",
    "\n",
    "**str = ’X-DSPAM-Confidence:0.8475’**\n",
    "\n",
    "**Use find and string slicing to extract the portion of the string after the colon\n",
    "character and then use the float function to convert the extracted string into a\n",
    "floating point number.**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0.8475\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "float"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str = 'X-DSPAM-Confidence:0.8475'\n",
    "pos = str.find(':')\n",
    "floatstr = float(str[pos+1:])\n",
    "print(floatstr)\n",
    "type(floatstr)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Exercise 6:\n",
    "Read the documentation of the string methods at**\n",
    "\n",
    "https://docs.python.org/3.5/library/stdtypes.html#string-methods\n",
    "\n",
    "**You might want to experiment with some of them to make sure you understand\n",
    "how they work. strip and replace are particularly useful.**\n",
    "\n",
    "**The documentation uses a syntax that might be confusing. For example, in\n",
    "find(sub[, start[, end]]), the brackets indicate optional arguments. So sub\n",
    "is required, but start is optional, and if you include start, then end is optional.**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "b'ABHISHEK'"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "name = 'ABHISHEK'\n",
    "name.encode(encoding=\"utf-8\", errors = \"strict\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [],
   "source": [
    "str = 'abhishek'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Abhishek'"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str.capitalize()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str.count('i', 2, 6)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str.isdigit()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str.isdecimal()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str.islower()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "str.istitle()"
   ]
  }
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