01_Variables.ipynb

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   "source": [
    "# Introduction à Python"
   ]
  },
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   "metadata": {},
   "source": [
    "> présentée par Loïc Messal"
   ]
  },
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   "source": [
    "## Introduction aux variables"
   ]
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   "source": [
    "L'encodage binaire de l'information est à la base de tout langage informatique. Les variables fournissent un accès à cette information contenue dans la mémoire de l'ordinateur.\n",
    "\n",
    "En programmation, il existe plusieurs types génériques pour les variables. Ils sont associés à une logique propre au langage pour pouvoir réaliser des opérations par la suite."
   ]
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     "text": [
      "3\n"
     ]
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   "source": [
    "# Ceci est un premier exemple\n",
    "a = 1  # a est une variable\n",
    "b = 2  # b est une variable\n",
    "resultat = a + b  # resultat est une variable contenant le résultat de l'addition de a et b\n",
    "print(resultat)  # print() permet d'afficher du texte dans la console"
   ]
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   "source": [
    "On retrouve les types classiques :\n",
    "- les booleans (booléens (oui, non))  : `bool` \n",
    "- les integers (nombres entiers)      : `int`\n",
    "- les floats   (nombre à virgules)    : `float`\n",
    "- les strings  (chaines de caractères): `str`\n",
    "\n",
    "Note : Il existe d'autres types usuels, que nous aurons l'occasion de voir par la suite. Commençons par ceux-là. Pour votre curiosité, un lien vers [une liste des types de bases de python](https://fr.wikiversity.org/wiki/Python/Les_types_de_base)."
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   "source": [
    "Les opérateurs vont agir différement selon le type de données qu'ils rencontrent. Les opérateurs usuels sont :\n",
    "- `+` (addition), \n",
    "- `-` (soustraction), \n",
    "- `*` (multiplication), \n",
    "- `/` (division),\n",
    "- `//` (division entière),\n",
    "- `%` (modulo),\n",
    "- `!` (négation),\n",
    "- `**` (exponentiation),\n",
    "- `==` (égalité),\n",
    "- `>` (supériorité)"
   ]
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   "source": [
    "bool(0) + bool(1)  # Addition entière"
   ]
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   "source": [
    "int(0) + int(1)  # Addition entière"
   ]
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     "data": {
      "text/plain": [
       "1.0"
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     "execution_count": 4,
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   "source": [
    "float(0) + float(1)  # Addition flottante"
   ]
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   "execution_count": 5,
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    {
     "data": {
      "text/plain": [
       "'01'"
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   "source": [
    "str(0) + str(1)  # Concaténation de caractères"
   ]
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   "source": [
    "En Python, les variables sont typées de manière implicite, c'est à dire qu'il n'est pas nécessaire de rajouter `bool()`, `int()`, `float()` ou `str()` à chaque fois qu'une variable est utilisée. Le type est défini par la manière dont on déclare ces variables."
   ]
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   "source": [
    "Soyez vigilant, ce comportement vous causera certainement des troubles à l'avenir, croyez moi."
   ]
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   "source": [
    "## Exemple de déclaration de variables"
   ]
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   "source": [
    "### Les booléens"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 6,
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   "source": [
    "True"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 7,
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   ],
   "source": [
    "False"
   ]
  },
  {
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   },
   "source": [
    "### Les entiers"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3"
      ]
     },
     "execution_count": 8,
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   ],
   "source": [
    "3"
   ]
  },
  {
   "cell_type": "markdown",
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     "slide_type": "subslide"
    }
   },
   "source": [
    "### Les flottants"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3.0"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "3.0"
   ]
  },
  {
   "cell_type": "markdown",
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     "slide_type": "subslide"
    }
   },
   "source": [
    "### Les strings"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "'JLR'"
      ]
     },
     "execution_count": 10,
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    }
   ],
   "source": [
    "\"JLR\""
   ]
  },
  {
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   "metadata": {
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     "slide_type": "slide"
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   },
   "source": [
    "## Exemple d'opérateurs"
   ]
  },
  {
   "cell_type": "markdown",
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   },
   "source": [
    "### Les booléens"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 11,
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   ],
   "source": [
    "not True  # Négation"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 12,
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   "source": [
    "True and False  # Et logique"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
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     "execution_count": 13,
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   "source": [
    "True or False  # Ou logique"
   ]
  },
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   "source": [
    "### Les entiers"
   ]
  },
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "8"
      ]
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     "execution_count": 14,
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   "source": [
    "5 + 3  # addition entière"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "15"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "5 * 3"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "1.6666666666666667"
      ]
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     "execution_count": 16,
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   "source": [
    "5 / 3  # division flottante"
   ]
  },
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   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "scrolled": true
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   "outputs": [
    {
     "data": {
      "text/plain": [
       "1"
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     "execution_count": 17,
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   "source": [
    "5 // 3  # division entière"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "2"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
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   "source": [
    "5 % 3  # modulo (reste de la division entière)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "125"
      ]
     },
     "execution_count": 19,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "5 ** 3  # exponentiation"
   ]
  },
  {
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     "slide_type": "subslide"
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   },
   "source": [
    "### Les flottants"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "5.0"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "3.0 + 2.0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "6.0"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "3.0 * 2.0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1.5"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "3.0 / 2.0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "9.0"
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "3.0 ** 2.0"
   ]
  },
  {
   "cell_type": "markdown",
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     "slide_type": "subslide"
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   },
   "source": [
    "### Les strings"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'JLRJakarto'"
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "\"JLR\" + \"Jakarto\"  # Concatenation"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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     "slide_type": "slide"
    }
   },
   "source": [
    "## Exemples de l'importance du typage"
   ]
  },
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   "execution_count": 25,
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     "slide_type": "subslide"
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    {
     "data": {
      "text/plain": [
       "'JLR JLR JLR '"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "\"JLR \" * 3  # Peut-on donner un sens à cette opération ?"
   ]
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  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
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   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "can't multiply sequence by non-int of type 'float'",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-26-c983496b611a>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m()\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[1;34m\"JLR \"\u001b[0m \u001b[1;33m*\u001b[0m \u001b[1;36m5.0\u001b[0m  \u001b[1;31m# Et à celle-ci ?\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m: can't multiply sequence by non-int of type 'float'"
     ]
    }
   ],
   "source": [
    "\"JLR \" * 5.0  # Et à celle-ci ?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "slide"
    }
   },
   "source": [
    "[Prochain chapitre : Les variables plus complexes](02_Variables_plus_complexes.ipynb)"
   ]
  }
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