04 Python的控制流.ipynb

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   "source": [
    "## 布尔值与布尔运算\n",
    "\n",
    "Python把0、空字符串’'和None看成 False，其他数值和非空字符串都看成 True"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
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     "data": {
      "text/plain": [
       "False"
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     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "bool(0)"
   ]
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   "cell_type": "code",
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   "metadata": {
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
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   "source": [
    "bool(None)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "scrolled": true
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "bool('')"
   ]
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  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
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     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "bool([])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
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     "execution_count": 11,
     "metadata": {},
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   "source": [
    "bool({})"
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  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
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     "execution_count": 12,
     "metadata": {},
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   "source": [
    "bool(())"
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  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "False\n",
      "False\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "print(True and True)\n",
    "print(True and False)\n",
    "print(False and True)\n",
    "print(False and False)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "True\n",
      "True\n",
      "True\n",
      "False\n"
     ]
    }
   ],
   "source": [
    "print(True or True)\n",
    "print(True or False)\n",
    "print(False or True)\n",
    "print(False or False)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "False\n",
      "True\n"
     ]
    }
   ],
   "source": [
    "print(not True)\n",
    "print(not False)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 比较运算符\n",
    "\n",
    "# x == y\tx 等于y\n",
    "# x < y\tx 小于y\n",
    "# x > y\tx 大于y\n",
    "# x >= y\tx 大于或等于y\n",
    "# x <= y\tx 小于或等于y\n",
    "# x != y\tx 不等于y\n",
    "# x is y\tx 和y 是同一个对象\n",
    "# x is not y\tx 和y 是不同的对象\n",
    "# x in y\tx 是容器（如序列）y 的成员\n",
    "# x not in y\tx 不是容器（如序列）y 的成员"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## if，else 语句"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# if and else\n",
    "\n",
    "name = input('What is your name?')\n",
    "if name.endswith('Gumby'):\n",
    "    # 除了endswith，还有startswith\n",
    "    print('Hello, Mr. Gumby')\n",
    "else:\n",
    "    print('Hello, stranger')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# elif\n",
    "\n",
    "name = input('What is your name? ')\n",
    "if name.endswith('Gumby'):\n",
    "    if name.startswith('Mr.'):\n",
    "        print('Hello, Mr. Gumby')\n",
    "    elif name.startswith('Mrs.'):\n",
    "        print('Hello, Mrs. Gumby')\n",
    "    else:\n",
    "        print('Hello, Gumby')\n",
    "else:\n",
    "    print('Hello, stranger')"
   ]
  }
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