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    "## ``Q8.`` ##    \n",
    "\n",
    "## ```Using Regular Expressions, develop a Python program to``` ##    \n",
    "\n",
    "## ```a) Identify a word with a sequence of one upper case letter followed by lower case letters. ``` ##     \n",
    "\n",
    "## ```b) Find all the patterns of '1(0+)1' in a given string. ``` ##   \n",
    "\n",
    "## ```c) Match a word containing 'z' followed by one or more o's.``` ##    \n",
    "\n",
    "## ```Prompt the user for input. ``` ## "
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   "source": [
    "## -----------------------------------------------------------------------------------------------------------------------------"
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    "**Approach to identify a sequence of one upper case letter followed by lower case letters**\n",
    "\n",
    "To check if the sequence of one upper case letter followed by lower case letters we use regular expression ` [A-Z]+[a-z]+$`   \n",
    "\n",
    "**Approach to find the patterns of `1(0+)1` in a given string**    \n",
    "\n",
    "A string contains patterns of the form `1(0+)1` where `(0+)` represents any non-empty consecutive sequence of 0's. \n",
    "\n",
    "First compile a pattern which follows `1(0+)1` using re.compile(regex) method. Search a first sub-string in original string which follows `1(0+)1` pattern using `pattern.search(string)` method.\n",
    "\n",
    "`substr = pattern.search(string)` returns `None` if it doesn't find the given regex as sub-string in original string otherwise it returns first matched sub-string which follows `1(0+)1` pattern.   \n",
    "\n",
    "`substr.start()` gives us starting index of matched regex and `substr.end()` gives us ending index of matched regex.\n",
    "Whenever we find regex as sub-string then increase count by 1 and again search for given regex starting from ending index of previous sub-string. *__The patterns are allowed to overlap.__*\n",
    "\n",
    "**Approach to match a word consisting of `z` followed by one or more `o's`**\n",
    "\n",
    "Compile a pattern which follows `zo+\\w*`, that matches a word which contains `'z'` followed by one or more `o's`.  \n",
    "\n",
    "Then pass a string to the `findall()` method. This method returns the list of the matched strings. If the length of this list is equal to zero then it doesn't contain a matched string.\n",
    "\n",
    "`\\w` `->` `represents any letter, numeric digit, or the underscore character.`  \n",
    "\n",
    "`*` `->` `means zero or more occurrence of the character.`  \n",
    "\n",
    "`+` `->` `means one or more occurrence of the character.`  "
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    "## -----------------------------------------------------------------------------------------------------------------------------"
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      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 1\n",
      "\n",
      "\n",
      "Enter a string with a sequence of Upper and Lower case letters: Arunachalpradesh\n",
      "\n",
      "\n",
      "String pattern match success \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 1\n",
      "\n",
      "\n",
      "Enter a string with a sequence of Upper and Lower case letters: madhyaPradesh\n",
      "\n",
      "\n",
      "String pattern match success \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 1\n",
      "\n",
      "\n",
      "Enter a string with a sequence of Upper and Lower case letters: MadhyaPradesh\n",
      "\n",
      "\n",
      "String pattern match success \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 1\n",
      "\n",
      "\n",
      "Enter a string with a sequence of Upper and Lower case letters: andhrapradesh\n",
      "\n",
      "\n",
      "String fails the pattern \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 2\n",
      "\n",
      "\n",
      "Enter a string in the form of 1(0+)1 pattern: 10101010001111\n",
      "\n",
      "\n",
      "The number of times the pattern appears in the string is 4 \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 2\n",
      "\n",
      "\n",
      "Enter a string in the form of 1(0+)1 pattern: 110\n",
      "\n",
      "\n",
      "The number of times the pattern appears in the string is 0 \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 3\n",
      "\n",
      "\n",
      "Enter a string: zoo\n",
      "\n",
      "\n",
      "String pattern match success \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 3\n",
      "\n",
      "\n",
      "Enter a string: zip\n",
      "\n",
      "\n",
      "No match \n",
      "\n",
      "1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\n",
      "2 --> Find all the patterns of '1(0+)1' in a given string\n",
      "3 --> Match a word containing 'z' followed by one or more o's\n",
      "4 --> Exit the program\n",
      "Enter a number to perform any of the operation: 4\n",
      "\n",
      "\n"
     ]
    }
   ],
   "source": [
    "import re\n",
    "\n",
    "\n",
    "# Function to Find all the patterns of \"1(0+)1\" in a given string\n",
    "def check_uc_lc_pattern(user_input):\n",
    "    # regex\n",
    "    pattern = re.compile(\"[A-Z]+[a-z]+$\")\n",
    "\n",
    "    # searching pattern\n",
    "    if pattern.search(user_input):\n",
    "        print(\"String pattern match success \\n\")\n",
    "    else:\n",
    "        print(\"String fails the pattern \\n\")\n",
    "\n",
    "\n",
    "def count_pattern(user_input):\n",
    "    # search regex '10+1' in original string search() function return first occurrence\n",
    "    # of regex '10+1' otherwise None '10+1' means sub-string starting and ending with 1\n",
    "    # and at least 1 or more zeros in between\n",
    "    count = 0\n",
    "    pattern = re.compile(\"10+1\")\n",
    "    substr = pattern.search(user_input)\n",
    "\n",
    "    # search for regex in original string until we are done with complete string\n",
    "    while substr != None:\n",
    "        # if we find any occurrence then increase count by 1\n",
    "        count = count + 1\n",
    "\n",
    "        # find next occurrence just after previous sub-string for first occurrence of the pattern\n",
    "        user_input = user_input[(substr.end() - 1) :]\n",
    "        substr = pattern.search(user_input)\n",
    "    print(f\"The number of times the pattern appears in the string is {count} \\n\")\n",
    "\n",
    "\n",
    "def z_followed_by_o(user_input):\n",
    "    # Regex \\w * zo+\\w * will match text that contains 'z', followed by one or more 'o'\n",
    "    pattern = re.compile(\"zo+\\w*\")\n",
    "\n",
    "    # The findall() method returns all matching strings of the regex pattern\n",
    "    match_object = pattern.findall(user_input)\n",
    "\n",
    "    # If length of match_object is not equal to zero then it contains matched string\n",
    "    if len(match_object) != 0:\n",
    "        print(\"String pattern match success \\n\")\n",
    "    else:\n",
    "        print(\"No match \\n\")\n",
    "\n",
    "\n",
    "def menu():\n",
    "    while True:\n",
    "        print(\n",
    "            \"1 --> Identify a word with a sequence of one upper case letter followed by lower case letters\"\n",
    "        )\n",
    "        print(\"2 --> Find all the patterns of '1(0+)1' in a given string\")\n",
    "        print(\"3 --> Match a word containing 'z' followed by one or more o's\")\n",
    "        print(\"4 --> Exit the program\")\n",
    "        choice = int(input(\"Enter a number to perform any of the operation: \"))\n",
    "        print(\"\\n\")\n",
    "        if choice == 1:\n",
    "            user_input = input(\n",
    "                \"Enter a string with a sequence of Upper and Lower case letters: \"\n",
    "            )\n",
    "            print(\"\\n\")\n",
    "            check_uc_lc_pattern(user_input)\n",
    "        elif choice == 2:\n",
    "            user_input = input(\"Enter a string in the form of 1(0+)1 pattern: \")\n",
    "            print(\"\\n\")\n",
    "            count_pattern(user_input)\n",
    "        elif choice == 3:\n",
    "            user_input = input(\"Enter a string: \")\n",
    "            print(\"\\n\")\n",
    "            z_followed_by_o(user_input)\n",
    "        else:\n",
    "            break\n",
    "\n",
    "\n",
    "# Main\n",
    "if __name__ == \"__main__\":\n",
    "    menu()"
   ]
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