On 16/02/2015 08:24, Alan Gauld wrote:
On 16/02/15 01:26, Tina Figz wrote:
I'm having a problem with my program and I'm not sure how to correct it
(I'm in an intro programming class).
My program is supposed two numbers and count the number of carry
operations.
This is what I have:
n1 = int(raw_input('Number #1: '))
n2 = int(raw_input('Number #2: '))
add = n1 + n2
> print ' '
> print n1, '+', n2, '=', add
Down to here everything is ok and you get the sum of the two numbers
sn1 = str(n1)
sn2 = str(n2)
num1 = 1
num2 = 1
num1 == num2
This line doesn't do anything.
last_n1 = sn1[-num1]
last_n2 = sn2[-num2]
int_lastn1 = int(last_n1)
int_lastn2 = int(last_n2)
eq = int_lastn1 + int_lastn2
carry = 0
Before entering the loop you have (for your example)
sn1 = '239', sn2 = '123' num1 = 1, num2 = 1
last_n1 = '9',last_n2 = '3', int_lastn1 = 9, int_lastn2 = 3
eq = 12
carry = 0
while eq >= 10 and carry < len(sn1) and carry < len(sn2):
num1 += 1
num2 += 1
carry += 1
Your loop only changes num1, num2 and carry.
But only carry is tested in the loop condition.
So in effect you just keep adding 1 to carry
until it is > then len(sn1 or len(sn2), ie 3.
You are not changing anything else, so you are effectively
just counting the number of characters in your shortest
number.
When I input 239 & 123 as my two numbers it equals 362, which is correct.
But it says I have 3 carries, when the answer should be 1 carry
operation.
You need to completely redesign your algorithm.
Try writing it out using pen and paper to figure
out how you would do it manually.
I'd start this exercise at line 1 and work right the way through the
code, e.g. why bother doing all the work to get sn1 and sn2?
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
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