"""
File: int_input.py
Author:  Mark Fienup with help from Intro. class
Description:  Implements a function int_input which validates an integer input.
"""
def int_input(prompt):
    """ Too simple since it does NOT allow for a sign (+,-) to preceed the digits"""
    while True:
        userInput = raw_input(prompt)
        if userInput.isdigit():
            return int(userInput)
        else:
            print "ERROR:  You can only enter digits"

def int_input2(prompt):
    """ Code developed in class on 2-16-10"""
    while True:
        userInput = raw_input(prompt)
        userInput = userInput.strip()
        negSignPosition = userInput.find('-')
        if negSignPosition == 0:
            isNegative = True
            userInput = userInput[1:].strip()
        else:
            isNegative = False
            if userInput.startswith('+'):
                userInput = userInput[1:].strip()
        if userInput.isdigit():
            if isNegative:
                return -1 * int(userInput)
            else:
                return int(userInput)
        else:
            print "ERROR:  You can only enter a sign followed by digits"

def int_input3(prompt):
    """ Slightly more readable verision of the class code"""
    while True:
        userInput = raw_input(prompt)
        userInput = userInput.strip()
        multiplier = +1
        if len(userInput) == 0:
            print "ERROR:  You can only enter a sign followed by digits:"
            continue
        elif userInput[0] == '+':
            userInput = userInput[1:]
        elif userInput[0] == '-':
            userInput = userInput[1:]
            multiplier = -1
        userInput = userInput.strip()
        if userInput.isdigit():
            return multiplier * int(userInput)
        else:
            print "ERROR:  You can only enter a sign followed by digits"



while True:
    x = int_input2("Enter an integer: ")
    print "Your integer was:",x