Splitting a string to do some math yields strange result, in Python

Question

So I'll admit that this is a homework assignment, but I'm not asking you all to do it for me, I'm just looking for some guidance. We need to make a Python program to accept a time in Hours:Minutes (2:30) format in a single string, and output the amount of time in minutes. (i.e. 2 hours and 30 minutes = 150 minutes)

I still need to work out some limitations for the string input:

1. Make sure it only uses digits and a colon
2. Make sure it can only accept five characters (##:##)
3. Make sure that the middle character is a colon (i.e. numbers are in correct order)
4. and make sure that if a time like 4:35 was entered, that a zero would be added in front automatically

I'll work on that later — for now I decided to work on the math I would get from the input.

It made sense to me to slice the string into two parts: hours and minutes. I then multiplied the amount of hours by 60 and added them to the pre-existing minutes to get a total amount of minutes. However, right now, entering a time like 02:45 is outputting a minute amount of 02020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020245.

Any idea what might be going wrong here? Just to be clear, this is homework and I want to work out the input limitations on my own, I just need help moving past this math issue.

#Henry Quinn - Python Advanced 4.0 Hours and Minutes
import re
print "This program takes an input of time in hours and minutes and outputs the amount    of minutes."
count = 0

#I still need to work out while loop
#Supposed to make sure that a time is entered correctly, or error out
while (count <1):
    time = raw_input("Please enter the duration of time (ex: 2:15 or 12:30): ")
    if not re.match("^[0-9, :]*$", time):
        print "Sorry, you're only allowed to use the numbers 0-9."
    elif len(time) > 5:
        print "Sorry, only five characters max allowed."
#MAKE THIS CHECK FOR A COLON
#elif
#elif
    else:
        count = count + 1

#If time = 12:45, hours should be equal to 12, and minutes should be equal to 45
hours = time[:2]
minutes = time[3:]

#Should convert hours to minutes
newhours = hours * 60

#Should make total amount of minutes
totalminutes = newhours + minutes

print "The total amount of elapsed minutes is %s" % (totalminutes)

raw_input("Please press Enter to terminate the program.")

Answer 1

Right now, hours and minutes are string variables, not ints. Thus, you can't multiply them as you would a number.

Change lines 20 and 21 to

hours = int(time[:2])
minutes = int(time[3:])

And putting in 02:45 should work. However, you will still run into problems if you don't have that leading 0 (like if you put in 2:45), so might I suggest you instead split it around the ":", like so:

hours = int(time.split(":")[0])
minutes = int(time.split(":")[1])