[Tutor] figured it out

[denis]

----- Original Message -----
From: <Simonjthecat at aol.com>
To: <tutor at python.org>
Sent: Friday, April 23, 2004 6:21 AM
Subject: [Tutor] figured it out


> Ok... with a little trial and error I figured it out by myself (yay!  this
is
> my first working program!)  I'll go ahead and put what I came up w/....
Is
> this the most efficient way?  It seemed kinda weird to define shape as the
same
> thing twice but it works.
> Here it is.
>
> import sys #for exit command
> shape = raw_input("Which shape[1,2,3,quit]? ")
>
> while shape != 'quit':
>    print """
>    Choose a shape from the list:
>    1) Triangle
>    2) Square
>    3) Circle
>    """
>    # note must now test for character '1' not
>    # number 1 coz raw_input returns strings not numbers
>    if shape == '1':     # a triangle
>       ht = input('What is the height of your triangle? ')
>       base = input('How long is the base? ')
>       print "The triangle's area is: ", 0.5*base*ht
>
>    elif shape == '2':   # square
>       side = input("How long are the square's sides? ")
>       print "The square's area is: ", side*side
>
>    elif shape == '3':   # a circle
>       rad = input('What radius is your circle? ')
>       print "The circle's area is: ", 3.14159*rad*rad
>
>    elif shape == 'quit':
>       sys.exit()
>
>    else:
>       print "Sorry, You didn't enter a valid choice"
>
>    shape = raw_input("Which shape[1,2,3,quit]? ")

In fact here your start condition "shape != 'quit'" will never be tested
True, even if looks like it is what lets the program exit the loop. As soon
as the user chooses 'quit', the program sys.exits . All right ? You could
have written "while True" or "while 1" instead. You force a hard loop exit
whit the program end.
Thus, you have to choose between sys.exit or standard program ending with
the last instruction in the file ; and between loop exit by testing shape !=
'quit' at the start.

Two more notes :
* fix the user interaction default(s)
* find a way of cancelling the first shape = raw_input() outside the loop


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