a solution to an exercise!

calculator.ipynb

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  {
   "cells": [
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "<font color='red'> The calculator </font>"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<font color='darkblue'>A possible solution to the exercise. You can copy and paste this code, and you should **write comments** as you understand what it is doing.</font>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def sumab (a,b):\n",
      "    res = a\n",
      "    for i in range(b):\n",
      "        res+=1\n",
      "    return res\n",
      "\n",
      "def subab (a,b):\n",
      "    res = a\n",
      "    for i in range(b):\n",
      "        res-=1\n",
      "    return res\n",
      "\n",
      "def multab(a,b):\n",
      "    res=0\n",
      "    for i in range(b):\n",
      "        res=sumab(res,a)\n",
      "    return res\n",
      "\n",
      "def divab(a,b):\n",
      "   \n",
      "    res=a\n",
      "    count=1\n",
      "    go=True\n",
      "    while res>0 or go:\n",
      "        res=subab(res,b)\n",
      "        if res<b:\n",
      "            go=False\n",
      "            break\n",
      "        else: \n",
      "            count+=1\n",
      "    return count\n",
      "\n",
      "def calculator(num1,num2,op):\n",
      "    if op in ['+']:\n",
      "        message=\"%g %s %g equals %g\"%(num1,op,num2,sumab(num1,num2) )\n",
      "        return message\n",
      "    if op in ['-']:\n",
      "        message=\"%g %s %g equals %g\"%(num1,op,num2,subab(num1,num2) )\n",
      "        return message\n",
      "    if op in ['x']:\n",
      "        message=\"%g %s %g equals %g\"%(num1,op,num2,multab(num1,num2) )\n",
      "        return message\n",
      "    if op in ['/']:\n",
      "        if num2==0:\n",
      "            return \"b is ZERO...aborting\" \n",
      "        elif num1<num2:\n",
      "            return \"%g %s %g equals %g\"%(num1,op,num2,0 )\n",
      "        elif num1==num2:\n",
      "            return 1\n",
      "        else:\n",
      "            message=\"%g %s %g equals %g\"%(num1,op,num2,divab(num1,num2) )\n",
      "            return message"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print calculator(10,33,'+')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 + 33 equals 43\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print calculator(20,15,'-')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "20 - 15 equals 5\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print calculator(15,12,'x')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "15 x 12 equals 180\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print calculator(100,220,'/')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 / 220 equals 0\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print calculator(100,30,'/')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100 / 30 equals 3\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "print calculator(1000,25,'/')"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "1000 / 25 equals 40\n"
       ]
      }
     ],
     "prompt_number": 7
    }
   ],
   "metadata": {}
  }
 ]
}