[Tutor] First program

[Andre Engels]

On 3/12/10, yd <ydmt923 at gmail.com> wrote:
> Hi,
> I am new to programming, altough i have read a few books about OOP and
> O'Reily's Learning Python.
> I would like some critique on my first program, is it normal for it to be
> this long to do something simple?

Well, many of your lines are user interface. Writing two lines of text
to the user will in general cost you (at least) two lines of code.

> I know i could have turned some of these things into classes and functions
> but i don't know how to do that yet.

I definitely see use for functions (long lists of if...elif.. are
usually better modeled using functions and a dictionary); using
classes feels like overkill for something this simple.

> Some critique of the algorithm and writing style or anything in general
> would help and any pointers would be appreciated.

General remark: The usual number of spaces indented per level is 4,
rather than the 2 that you use. This makes it easier to see the
indentation level at first glance.

> #title Area calculator
> #author Yudhishthir Singh
>
>
> #welcome screen
> msg = 'Welcome to the area calculator program '
> print(msg)
> print('-'*len(msg))
> loop = 'y'
> print()
> while loop == 'y':
>   #Choices menu
>   print('Please select a shape\n')
>   print('1. Rectangle')
>   print('2. Square')
>   print('3. Parallelogram ')
>   print('4. Trapezoid ')
>   print('5. Circle ')
>   print('6. Ellipse')
>   print('7. Traingle\n')
>   print('-'*len(msg))
>   choice = input('\nPlease enter your choice: ')
>   if choice.isdigit() ==True:
>     choice = int(choice)

1. The if can be shortened to

if choice.isdigit():

2. This thing can be removed completely if you chance the if-statements below to

if choice == "1"

etcetera.

>   if choice ==1:
>     #Rect
>     height = input('please enter the height: ')
>     width = input('please enter the width: ')
>     height = int(height)
>     width = int(width)
>     areaRectangle = height*width
>     print('\nThe area of a rectangle with {0} height and {1} width is
> '.format(height,width),areaRectangle,'\n')

I think it's ugly to mix styles here - either use format or use commas, not both

>   elif choice ==2:
>     #Square
>     side = input('enter the height or width: ')
>     side = int(side)
>     areaSquare = side**2
>     print('\nThe area of a square with a height or width of {0} is
> '.format(side), areaSquare,'\n')
>   elif choice ==3:
>     #Parallelogram
>     height = input('enter the height: ')
>     base = input('enter the width aka base: ')
>     height = int(height)
>     base = int(base)
>     areaParallelogram = height*base
>     print('\nThe area of a parrallelogram with height {0} and width {1} is
> '.format(height,base), areaParallelogram,'\n')
>   elif choice ==4:
>     #Trapezoid
>     height = input('enter the height: ')
>     base1 = input('enter the width of shorter side: ')
>     base2 = input('enter the width of longer side: ')
>     height = int(height)
>     base1 = int(base1)
>     base2 = int(base2)
>     areaTrapezoid = (height/2)*(base1+base2)
>     print('\nThe area of a trapezoid with height {0} ,base {1} and {2} is
> '.format(height,base1,base2), areaTrapezoid, '\n')
>   elif choice ==5:
>     #Circle
>     radius = input('radius: ')
>     radius = int(radius)
>     areaCircle = 3.14*(radius**2)
>     print('\nThe area of a circle with radius {0} is '.format(radius),
> areaCircle, '\n')
>   elif choice ==6:
>     #Ellipse
>     radius1 = input('enter length of radius 1: ')
>     radius2 = input('enter length of radius 2: ')
>     radius1 = int(radius1)
>     radius2 = int(radius2)
>     areaEllipse = 3.14*radius1*radius2
>     print('\nThe area of an ellipse with radii of length {0} and {1} is
> '.format(radius1,radius2), areaEllipse, '\n')
>   elif choice ==7:
>     #Triangle
>     base = input('enter base: ')
>     height = input('enter height: ')
>     base = int(base)
>     height = int(height)
>     areaTriangle = (1/2 *base)*height
>     print('\nThe area of a triange with height {0} and base {1} is
> '.format(height,base), areaTriangle, '\n')
>   else:
>     raise Exception('{0}, is not a valid choice'.format(choice))

This will cause the program to stop-with-error if something wrong is
entered. I think that's quite rude. I would change this to:
  else:
    print('{0}, is not a valid choice'.format(choice))

>   loop = input('Do you want to calculate the area of another shape? Y/N: ')
>   loop = loop.lower()



-- 
André Engels, andreengels at gmail.com