attempting to add cost from the end of a line but only getting a blank space

Question

I'm attempting to get the cost (the values at the end of each line) total from all the logs but when price is printed it doesn't print anything just a blank space. Each line has varying length before the value. This code does not yet add the cost but I'm making sure I'm getting.

log record entered into function (rec.dat): *this log would be the record entered into the function

@ 2014 2 14 00:03:01 Matt "login" 0.01

@ 2014 2 14 02:06:12 Mary "login" 0.01

@ 2014 2 14 17:12:05 Mary "cd ~/cs150/projects" 0.01

function: the goal of the function is to add how much the cost would be for all actions (in this case cost should end up totaling .03)

def cost(rec):
    s = Scanner(rec)
    cost = 0
    line = s.readline()
    for i in range(0, len(rec), 1):
        info = len(line) - 3
        price = line[info:0]
        print("price: ",price)
        cost += price
        line = s.readline()
    s.close()
    return cost

Answer 1

Make that:

price = line[-3:]

You can delete info completely. Look up how Python's slice notation works, it provides handy shortcuts for a large number of problems, including yours :-)

Answer 2

It seems to me 'price = line[info:0] needs to be 'price = line[info:]'

>>> a = 'abcde'
>>> a[2:]
'cde'
>>> a[2:0]
''
>>>