Parse numbers from strings and sum them

sum_nums.py

"""
Proof of concept

Someone wanted to parse number from random strings and sum them as part of some school project.

@author: Matthew Purdon
"""
from __future__ import print_function
import sys


def parse_string(string):
	result = 0

	sign = 1
	numbers = []
	current_number = ''
	for character in string:
		print("Processing character {}".format(character))

		if character.isdigit():
			print("+++ appended to current number")
			current_number += character
		else:
			if character == '-':
				print("--- negating current number")
				sign = -1
				continue

			if current_number:
				current_number = sign * int(current_number)
				print ("*** appending {} to list of numbers".format(current_number)) 
				numbers.append(current_number)
				sign = 1
				current_number = ''

			continue

	if current_number:
		current_number = sign * int(current_number)
		print ("*** appending {} to list of numbers".format(current_number)) 
		numbers.append(current_number)


	print("Summing numbers {}".format(numbers))
	return sum(numbers)


def main():
	strings = [
		"--1a2b-3c",
		"123ab!45c",
		"abcdef",
		"0123.4",
		"dFD$#23+++12@#T1234;/.,10",
	]

	for string in strings:
		print ("{} = {}\n\n".format(string, parse_string(string)))

	return 0


if __name__ == "__main__":
	sys.exit(main())