loops

Loops.ipynb

{
 "cells": [
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Loops"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## For loop"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "animels = ['cat', 'dog', \"mouse\"]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "cat\n",
      "dog\n",
      "mouse\n"
     ]
    }
   ],
   "source": [
    "for animel in animels:\n",
    "    print(animel)\n",
    "# this iterates over the list, and assign the next value into animel each time"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "1\n",
      "2\n"
     ]
    }
   ],
   "source": [
    "for i in range(3): # range gives numbers from 0 to 3\n",
    "    print(i)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## While loops"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "4\n",
      "3\n",
      "2\n",
      "1\n",
      "-4\n",
      "-3\n",
      "-2\n",
      "-1\n"
     ]
    }
   ],
   "source": [
    "x = 4\n",
    "while x:\n",
    "    print(x)\n",
    "    x = x - 1\n",
    "# when x is 0, the while statement is false, and we leave\n",
    "\n",
    "# this is the same as\n",
    "x = -4\n",
    "while x != 0:\n",
    "    print(x)\n",
    "    x = x + 1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Continue and Break"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "# continue moves into the next line of iteration, break exit the loop"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "cat doesnt have an o in its name\n"
     ]
    }
   ],
   "source": [
    "for animel in animels:\n",
    "    if 'o' in animel:\n",
    "        continue\n",
    "    else:\n",
    "        print(animel, 'doesnt have an o in its name')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10\n",
      "9\n",
      "8\n"
     ]
    }
   ],
   "source": [
    "x = 10\n",
    "while True: # suppose to never end\n",
    "    print(x)\n",
    "    x = x - 1\n",
    "    if x == 7:\n",
    "        break  # saves us from an endless loop"
   ]
  }
 ],
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