transfer_value_user_input.py

# Will ask the user to enter the amount and Units (Iota, MegaIota, GigaIota,etc.)
def transfer_value_user_input():
    print("\n\nEnter a number and the the unit size.\n"
          "Avaliable units are \"i\"(Iota), \"ki\"(KiloIota), \"mi\"(MegaIota), "
          "\"gi\"(GigaIota) and \"ti\"(TerraIota)\n"
          "Example: If you enter \"12.3 gi\", I will send 12.3 GigaIota\n")
    ask_user = True
    while ask_user:
        user_input = raw_input("Please enter the amount to send: ")
        user_input = user_input.upper()
        user_input_as_list = list(user_input)

        allowed_characters = list("1234567890. IKMGT")
        allowed_for_numbers = list("1234567890.")
        allowed_for_units = list("iIkKmMgGtT")
        is_valid = True

        value = ""
        unit = ""
        i = 0
        while i < len(user_input_as_list):
            char = user_input_as_list[i]
            if char in allowed_characters:
                if char in allowed_for_numbers:
                    value += char
                elif char in allowed_for_units:
                    unit += char
            else:
                is_valid = False
            i += 1
        if is_valid:
            try:
                value = float(value)

                if unit == "I":
                    value = value
                    if 1 > value > 0:
                        print("You entered a amount greater then 0 but smaller then 1 Iota!\n"
                              "Can only send whole Iotas...\n ")
                    else:
                        return int(value)

                elif unit == "KI":
                    value *= 1000
                    if 1 > value > 0:
                        print("You entered a amount greater then 0 but smaller then 1 Iota!\n"
                              "Can only send whole Iotas...\n ")
                    else:
                        return int(value)

                elif unit == "MI":
                    value *= 1000000
                    if 1 > value > 0:
                        print("You entered a amount greater then 0 but smaller then 1 Iota!\n"
                              "Can only send whole Iotas...\n ")
                    else:
                        return int(value)

                elif unit == "GI":
                    value *= 1000000000
                    if 1 > value > 0:
                        print("You entered a amount greater then 0 but smaller then 1 Iota!\n"
                              "Can only send whole Iotas...\n ")
                    else:
                        return int(value)

                elif unit == "TI":
                    value *= 1000000000000
                    if 1 > value > 0:
                        print("You entered a amount greater then 0 but smaller then 1 Iota!\n"
                              "Can only send whole Iotas...\n ")
                    else:
                        return int(value)
                else:
                    print("You didn't enter a valid unit size! Please try again\n")

            except:
                print("You didn't enter a valid value! Please try again\n")

        else:
            print("You didn't enter a valid value! Please try again\n")