[Tutor] Creating an Invalid Message for user
Alan Gauld
alan.gauld at btinternet.com
Sat Apr 19 02:18:08 CEST 2014
On 18/04/14 22:19, Saba Usmani wrote:
> I am meant to design code for a program that converts from binary number
> to decimal and vice versa.
First, you know that python includes functions for doing that already
right? So you are just doing this as a learning exercise?
> while loop:
> bord = raw_input("Enter b for binary or d decimal or exit to exit")
> if bord == "b":
> d = 0
> b = 0
> factor = 1;
> b = raw_input ("Enter Binary Number:")
> b=b.lstrip("0")
Before converting to an int check each character is in the numeric range
you need. For binary thats like
for ch in inputstring:
if ch not in "01":
# process invalid input
For decimal its
for ch in inputstring:
if ch not in "0123456789":
# process bad input.
You could put that in a function and pass in the
numbers as a parameter...
If you accept floats as input then it gets a whole
lot more complicated. but you are converting to int
so I assume its ints you expect.
HTH
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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