06. Functions/2. Scope of Variables.ipynb

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    "er.pranavsinha@gmail.com"
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   "source": [
    "### SCOPE OF VARIABLES"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n"
     ]
    }
   ],
   "source": [
    "a1 = 10 #Global Variable\n",
    "\n",
    "def f():\n",
    "    b1 = 12 # local Variable\n",
    "\n",
    "print(a1)    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
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   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'b1' is not defined",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-2-681d807e296d>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m      4\u001b[0m     \u001b[0mb1\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m12\u001b[0m \u001b[1;31m# local Variable\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      5\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 6\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mb1\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m: name 'b1' is not defined"
     ]
    }
   ],
   "source": [
    "a1 = 10 #Global Variable\n",
    "\n",
    "def f():\n",
    "    b1 = 12 # local Variable\n",
    "\n",
    "print(b1)  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "a1 = 10 #Global Variable\n",
    "\n",
    "def f():\n",
    "    b1 = 12 # local Variable\n",
    "\n",
    "f()  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "scrolled": true
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "12\n"
     ]
    }
   ],
   "source": [
    "a1 = 10 #Global Variable\n",
    "\n",
    "def f():\n",
    "    b1 = 12 # local Variable\n",
    "    print(b1)  \n",
    "f()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n",
      "12\n",
      "10\n"
     ]
    }
   ],
   "source": [
    "# can print G in function\n",
    "a2 =10 #G\n",
    "\n",
    "def f2():\n",
    "    b2 = 12 #L\n",
    "    print(b2)\n",
    "    print(a2) #3RD CALLED\n",
    "\n",
    "print(a2)   # 1st called \n",
    "f2() #2nd called"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n",
      "12\n",
      "10\n"
     ]
    }
   ],
   "source": [
    "# a3 printed because it in called before function.\n",
    "def f3():\n",
    "    b3 = 12\n",
    "    print(b3)\n",
    "    print(a3)\n",
    "a3 = 10\n",
    "\n",
    "print(a3)\n",
    "f3()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "scrolled": true
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "12\n"
     ]
    },
    {
     "ename": "NameError",
     "evalue": "name 'a4' is not defined",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-15-cc4f8b2df088>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m      4\u001b[0m     \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0ma4\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      5\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 6\u001b[1;33m \u001b[0mf4\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      7\u001b[0m \u001b[0ma4\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;36m10\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      8\u001b[0m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0ma4\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
      "\u001b[1;32m<ipython-input-15-cc4f8b2df088>\u001b[0m in \u001b[0;36mf4\u001b[1;34m()\u001b[0m\n\u001b[0;32m      2\u001b[0m     \u001b[0mb4\u001b[0m \u001b[1;33m=\u001b[0m\u001b[1;36m12\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      3\u001b[0m     \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mb4\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 4\u001b[1;33m     \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0ma4\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m      5\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      6\u001b[0m \u001b[0mf4\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n",
      "\u001b[1;31mNameError\u001b[0m: name 'a4' is not defined"
     ]
    }
   ],
   "source": [
    "#python ios confused what to print\n",
    "def f4():\n",
    "    b4 =12\n",
    "    print(b4)\n",
    "    print(a4)\n",
    "\n",
    "f4()    \n",
    "a4 = 10\n",
    "print(a4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "13\n",
      "12\n",
      "13\n"
     ]
    }
   ],
   "source": [
    "a5 = 13\n",
    "def f5():\n",
    "    a5 = 12\n",
    "    print(a5)\n",
    "    \n",
    "print(a5)\n",
    "f5()\n",
    "print(a5)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "13\n",
      "12\n",
      "140705596188800\n",
      "13\n",
      "140705596188832\n"
     ]
    }
   ],
   "source": [
    "# Python assume we wnat to create  local variable.\n",
    "a5 = 13\n",
    "def f5():\n",
    "    a5 = 12\n",
    "    print(a5)\n",
    "    print(id(a5))\n",
    "print(a5)\n",
    "f5()\n",
    "print(a5)\n",
    "print(id(a5))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "13\n",
      "12\n",
      "12\n"
     ]
    }
   ],
   "source": [
    "# Adding global \n",
    "a6 = 13\n",
    "def f6():\n",
    "    global a6\n",
    "    a6 = 12\n",
    "    print(a6)\n",
    "    \n",
    "print(a6)\n",
    "f6()\n",
    "print(a6)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "scrolled": false
   },
   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'b' is not defined",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-20-85b36586d09f>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[0;32m      3\u001b[0m \u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0;32m      4\u001b[0m \u001b[0mf\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 5\u001b[1;33m \u001b[0mprint\u001b[0m\u001b[1;33m(\u001b[0m\u001b[0mb\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m: name 'b' is not defined"
     ]
    }
   ],
   "source": [
    "def f():\n",
    "    b = 10\n",
    "\n",
    "f()\n",
    "print(b)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n"
     ]
    }
   ],
   "source": [
    "def f():\n",
    "    b = 10\n",
    "    return b\n",
    "\n",
    "x = f()\n",
    "print(x)"
   ]
  }
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