Notebooks/02_Flow_Control.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import time\n",
    "import sys\n",
    "import random"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Introduction to Python  \n",
    "\n",
    "# [Control Flow Commands](https://docs.python.org/3/tutorial/controlflow.html)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ _if_ , _elif_, _else_\n",
    "+ _for_\n",
    "+ _while_\n",
    "+ _break_, _continue_, _pass_\n",
    "+ _try_, _except_, _else_, _finally_"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Conditional: _if_  /  _elif_  /  _else_\n",
    "\n",
    "+ Python uses the control flow if/elif/else to evaluate expressions  \n",
    "+ Conditions can be evaluated as True or False  \n",
    "+ One block can contain one _if_ statement, zero, one or many _elif_ statements and zero or one _else_ statement.  "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Sintax:\n",
    "\n",
    "    if <condition>:  \n",
    "        code  \n",
    "    elif <condition>:     (optional)  \n",
    "        code  \n",
    "    elif <condition>:     (optional)  \n",
    "        code  \n",
    "    ...  \n",
    "    else:                 (optional)   \n",
    "        code  \n",
    "        \n",
    "### [Conditional Expression]() (Ternary Operator)\n",
    "\n",
    "    <expression> if <condition> else <other_expression>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Name does not start with T,U,V, X or Z\n",
      "Ending if statement\n"
     ]
    }
   ],
   "source": [
    "name = 'Matheus'\n",
    "\n",
    "if name.startswith('T'):\n",
    "    print(f'Name starts with {name[0]}')\n",
    "    print('I am here')\n",
    "elif name.startswith('U'):\n",
    "    print(f'Name starts with {name[0]} and ends with {name[-1]}')\n",
    "elif name.startswith('V'):\n",
    "    print(f'Name starts with {name[0]}')\n",
    "elif name.startswith('X'):\n",
    "    print(f'Name starts with {name[0]}')\n",
    "elif name.startswith('Z'):\n",
    "    print(f'Name starts with {name[0]}')\n",
    "else:\n",
    "    print('Name does not start with T,U,V, X or Z')\n",
    "\n",
    "print('Ending if statement')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Nested _if_ statements"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 38,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "the number is less or equal to 5\n"
     ]
    }
   ],
   "source": [
    "number = 4\n",
    "if number > 5:\n",
    "    print('greater than 5')\n",
    "    if number > 7:\n",
    "        print('greater than 7')\n",
    "    else:\n",
    "        print('lower or equal than 7')\n",
    "        if number > 3:\n",
    "            print('greater than 3')\n",
    "else:\n",
    "    print('the number is less or equal to 5')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### if, with ternary operator"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "done\n"
     ]
    }
   ],
   "source": [
    "x = \"do that\"\n",
    "if x == \"do that\":\n",
    "    print(\"done\")\n",
    "else:\n",
    "    print('not done')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "done\n"
     ]
    }
   ],
   "source": [
    "print(\"done\") if x == \"do that\" else print(\"not done\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Loops: the _for_ command"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ _for_ takes a sequence and loops through it, until it ends\n",
    "+ Each pass is called an _iteration_\n",
    "+ Any object that is _iterable_ can be passed to _for_ loops"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Sintax:\n",
    "\n",
    "    for <any_variable_name> in <any_iterable>:\n",
    "        code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "---\n",
      "2 Daysies\n",
      "\n",
      "---\n",
      "6 Daysies\n",
      "\n",
      "---\n",
      "10 Daysies\n",
      "\n"
     ]
    }
   ],
   "source": [
    "for integer in range(2,11,4):\n",
    "    print('---')\n",
    "    print(f'{integer} Daysies')\n",
    "    print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "9\n",
      "25\n",
      "49\n",
      "81\n"
     ]
    }
   ],
   "source": [
    "for number in range(1,10,2):\n",
    "    print(number**2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "M\n",
      "n\n",
      "e\n",
      "s\n",
      "i\n",
      "l\n",
      "J\n",
      "n\n"
     ]
    }
   ],
   "source": [
    "for letter in 'My name is Little John'[::3]:\n",
    "    print(letter)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 46,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1 1 1\n",
      "4 16 64\n",
      "8 64 512\n",
      "9 81 729\n",
      "10 100 1000\n"
     ]
    }
   ],
   "source": [
    "for element in [1,4,8,9,10]:\n",
    "    print(element, element**2, element**3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "4\n",
      "5\n"
     ]
    }
   ],
   "source": [
    "c = {1,4,4,4,4,5}\n",
    "for element in c:\n",
    "    print(element)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "k1\n",
      "k2\n"
     ]
    }
   ],
   "source": [
    "d = {\"k1\":1,\"k2\":2}\n",
    "for element in d:\n",
    "    print(element)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Loop with conditional: the comman _while_\n",
    "\n",
    "+ With _while_, you define a condition at the beggining\n",
    "+ While the condition is true, the loop will continue\n",
    "+ It is easy to create infinite loops with _while_"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Sintax:\n",
    "\n",
    "    while <condition>:\n",
    "        code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 57,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n",
      "6\n",
      "7\n",
      "8\n",
      "9\n"
     ]
    }
   ],
   "source": [
    "x = 1\n",
    "while x < 10:\n",
    "    print(x)\n",
    "    x += 1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Change flow behaviour with _break_, _continue_ and _pass_\n",
    "\n",
    "+ The _break_ statement, breaks out of the innermost enclosing for or while loop.\n",
    "+ The _continue_ statement continues with the next iteration of the loop.\n",
    "+ The _pass_ statement does nothing. It can be used when a statement is required syntactically but the program requires no action."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ ### break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 83,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "m\n",
      "y\n",
      " \n",
      "t\n"
     ]
    }
   ],
   "source": [
    "for letter in \"my text is not long\":\n",
    "    print(letter)\n",
    "    if letter == \"t\":\n",
    "        break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 93,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "5\n",
      "6\n",
      "7\n",
      "8\n",
      "9\n",
      "10\n"
     ]
    }
   ],
   "source": [
    "x = 0\n",
    "while True:\n",
    "    print(x)\n",
    "    x += 1\n",
    "    if x > 10:\n",
    "        break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 92,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Sum of first 120 integers is : 7260\n"
     ]
    }
   ],
   "source": [
    "numbers = range(1,1000)\n",
    "num_sum = 0  \n",
    "count = 0  \n",
    "\n",
    "for x in numbers:  \n",
    "    num_sum += x     # num_sum = num_sum + x\n",
    "    count += 1       # count = count + 1\n",
    "    if count == 120:  \n",
    "        break  \n",
    "print(f\"Sum of first {count} integers is : {num_sum}\")  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 90,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0.22832626605966955\n",
      "0.571566967737545\n",
      "0.2781761199384959\n",
      "0.7706084575991982\n",
      "0.7377463932107212\n",
      "0.42414418980421587\n"
     ]
    }
   ],
   "source": [
    "while True:\n",
    "    x = random.random()\n",
    "    print(x)\n",
    "    if 0.5 > x > 0.4:\n",
    "        break"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ ### continue"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 94,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n",
      "3\n",
      "4\n",
      "6\n",
      "8\n"
     ]
    }
   ],
   "source": [
    "for number in range(10):\n",
    "    if number in [5,7,9]:\n",
    "        continue\n",
    "    print(number)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 95,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "x equals to 1 and y equals to 2\n",
      "x equals to 7 and y equals to 9\n",
      "x equals to 1 and y equals to 7\n"
     ]
    }
   ],
   "source": [
    "for x,y in [(1,2),(3,6),(7,9),(3,4),(1,7)]:\n",
    "    if x == 3:\n",
    "        continue\n",
    "    print(f'x equals to {x} and y equals to {y}')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "+ ### pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 98,
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "unexpected EOF while parsing (<ipython-input-98-49f589c1b728>, line 1)",
     "output_type": "error",
     "traceback": [
      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-98-49f589c1b728>\"\u001b[0;36m, line \u001b[0;32m1\u001b[0m\n\u001b[0;31m    for x in range(10):     #error\u001b[0m\n\u001b[0m                                  ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m unexpected EOF while parsing\n"
     ]
    }
   ],
   "source": [
    "for x in range(10):     #error"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 99,
   "metadata": {},
   "outputs": [],
   "source": [
    "for x in range(10):\n",
    "    pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 100,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Current Letter : P\n",
      "Current Letter : y\n",
      "Current Letter : t\n",
      "This is a pass block\n",
      "Current Letter : h\n",
      "Current Letter : o\n",
      "Current Letter : n\n"
     ]
    }
   ],
   "source": [
    "for letter in 'Python': \n",
    "    if letter == 'h':\n",
    "        pass\n",
    "        print('This is a pass block')\n",
    "    print('Current Letter :', letter)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### _try_, _except_, _else_, _finally_, _raise_  \n",
    "\n",
    "[Exception types in Python](https://docs.python.org/3/tutorial/errors.html)  \n",
    "See also: [this](https://stackabuse.com/python-exception-handling/)\n",
    "\n",
    "+ _try_           lets you handle errors/exceptions in the code.  \n",
    "+ _except_        lets you take an action with this occurs.   \n",
    "+ _else_          lets you take an action when no error occurs.  \n",
    "+ _finally_       Lets you take an action no matter if errors ocurred or not.  \n",
    "+ _raise_         Allows the programmer to force a specified exception to occur."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Python Exceptions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 101,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "linux\n"
     ]
    }
   ],
   "source": [
    "print(sys.platform)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 104,
   "metadata": {},
   "outputs": [
    {
     "ename": "AssertionError",
     "evalue": "This code runs on Linux only.",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-104-a9e53cd18bc9>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0;32massert\u001b[0m \u001b[0;34m(\u001b[0m\u001b[0;34m'windows'\u001b[0m \u001b[0;32min\u001b[0m \u001b[0msys\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mplatform\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m\"This code runs on Linux only.\"\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      2\u001b[0m \u001b[0;31m#assert ('linux' in sys.platform), \"This code runs on Linux only.\"\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mAssertionError\u001b[0m: This code runs on Linux only."
     ]
    }
   ],
   "source": [
    "assert ('windows' in sys.platform), \"This code runs on Linux only.\"\n",
    "#assert ('linux' in sys.platform), \"This code runs on Linux only.\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 105,
   "metadata": {},
   "outputs": [
    {
     "ename": "FileNotFoundError",
     "evalue": "[Errno 2] No such file or directory: 'file.log'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mFileNotFoundError\u001b[0m                         Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-105-831e4333b419>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0;32mwith\u001b[0m \u001b[0mopen\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'file.log'\u001b[0m\u001b[0;34m)\u001b[0m \u001b[0;32mas\u001b[0m \u001b[0mfile\u001b[0m\u001b[0;34m:\u001b[0m    \u001b[0;31m# error\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      2\u001b[0m     \u001b[0mread_data\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mfile\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mread\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mFileNotFoundError\u001b[0m: [Errno 2] No such file or directory: 'file.log'"
     ]
    }
   ],
   "source": [
    "with open('file.log') as my_file:    # error\n",
    "    read_data = my_file.read()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 106,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Could not open file.log\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    with open('file.log') as my_file:\n",
    "        read_data = my_file.read()\n",
    "except:\n",
    "    print('Could not open file.log')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 112,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "unsupported operand type(s) for +: 'int' and 'list'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-112-6178ddc8ab8a>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0mx\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0my\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0;34m[\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 3\u001b[0;31m \u001b[0mx\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0my\u001b[0m \u001b[0;31m# error\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: unsupported operand type(s) for +: 'int' and 'list'"
     ]
    }
   ],
   "source": [
    "x = 2\n",
    "y = [1,3]\n",
    "x + y # error"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 108,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "An error has occurred with summing two variables\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    x + y \n",
    "except:\n",
    "    print(\"An error has occurred with summing two variables\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 110,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Everythink is ok\n"
     ]
    }
   ],
   "source": [
    "x,y = 2,3\n",
    "\n",
    "try:\n",
    "    x + y \n",
    "except:\n",
    "    print(\"An error has occurred\")\n",
    "else:\n",
    "    print(\"Everythink is ok\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 113,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "An error has occurred\n",
      "Ending try/except block\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    x + y \n",
    "except:\n",
    "    print(\"An error has occurred\")\n",
    "else:\n",
    "    print(\"Everythink is ok\")\n",
    "finally:\n",
    "    print(\"Ending try/except block\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 130,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<class 'TypeError'>\n",
      "Exception caught: unsupported operand type(s) for +: 'int' and 'list'\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    x + y \n",
    "except Exception as error:\n",
    "    print(type(error))\n",
    "    print(f\"Exception caught: {error}\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 119,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Type Error\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    x + [y] \n",
    "except TypeError:\n",
    "    print(\"Type Error\")\n",
    "except ValueError:\n",
    "    print(\"Value Error\")  \n",
    "except Exception as e:\n",
    "    print(\"Exception caught:\" + str(e))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Sintax Errors cannot be captured with try. See [this](https://stackoverflow.com/questions/25049498/failed-to-catch-syntax-error-python) post"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 121,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I/O error(2): No such file or directory\n"
     ]
    },
    {
     "ename": "FileNotFoundError",
     "evalue": "[Errno 2] No such file or directory: 'integers.txt'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mFileNotFoundError\u001b[0m                         Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-121-474eb7c7d31d>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;32mtry\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m     \u001b[0mf\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mopen\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'integers.txt'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      3\u001b[0m     \u001b[0ms\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mf\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mreadline\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      4\u001b[0m     \u001b[0mi\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ms\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mstrip\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      5\u001b[0m \u001b[0;32mexcept\u001b[0m \u001b[0mIOError\u001b[0m \u001b[0;32mas\u001b[0m \u001b[0me\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mFileNotFoundError\u001b[0m: [Errno 2] No such file or directory: 'integers.txt'"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    f = open('integers.txt')\n",
    "    s = f.readline()\n",
    "    i = int(s.strip())\n",
    "except IOError as e:\n",
    "    errno, strerror = e.args\n",
    "    print(\"I/O error({0}): {1}\".format(errno, strerror))\n",
    "    # e can be printed directly without using .args:\n",
    "    # print(e)\n",
    "except ValueError:\n",
    "    print(\"No valid integer in line.\")\n",
    "except Exception as e:\n",
    "    print(\"Exception caught:\" + str(e))\n",
    "    raise"
   ]
  }
 ],
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