Interactive input in python

Question

Here is the directions for what I need to do:

You are to write a complete program that obtains three pieces of data and then process them. The three pieces of information are a Boolean value, a string, and an integer. The logic of the program is this: if the Boolean value is True, print out the string twice, once with double quotes and once without - otherwise print out twice the number.

Here is what I have so far:

def main():
    Boolean = input("Give me a Boolean: ")
    String = input("Give me a string: ")
    Number = int(input("Give me a number: "))

Can anybody help me out?

Answer 1

On stackoverflow, we're here to help people solve problems, not to do your homework, as your question very likely sounds… That said, here is what you want:

def main():
    Boolean = input("Give me a Boolean: ")
    String = input("Give me a string: ")
    Number = int(input("Give me a number: "))

    if Boolean == "True":
        print('"{s}"\n{s}'.format(s=String))
    try:
        print('{}\n{}'.format(int(Number)))
    except ValueError as err:
        print('Error you did not give a number: {}'.format(err))

if __name__ == "__main__":
    main()

A few explanations:

• Boolean is "True" checks whether the contained string is actually the word True, and returns True, False otherwise.
• then the print(''.format()) builds the double string (separated by \n) using the string format.
• finally, when converting the string Integer into an int using int(Integer), it will raise a ValueError exception that gets caught to display a nice message on error.

the if __name__ == "__main__": part is to enable your code to be only executed when ran as a script, not when imported as a library. That's the pythonic way of defining the program's entry point.

Answer 2

I like to add a bit of logic to ensure proper values when I do input. My standard way is like this:

import ast
def GetInput(user_message, var_type = str):
    while 1:
        # ask the user for an input
        str_input = input(user_message + ": ")
        # you dont need to cast a string!
        if var_type == str:
            return str_input
        else:
            input_type = type(ast.literal_eval(str_input))
        if var_type == input_type:
            return ast.literal_eval(str_input)
        else:
            print("Invalid type! Try again!")

Then in your main you can do something like this!

def main():
    my_bool = False
    my_str = ""
    my_num = 0
    my_bool = GetInput("Give me a Boolean", type(my_bool))
    my_str = GetInput("Give me a String", type(my_str))
    my_num = GetInput("Give me a Integer", type(my_num))

    if my_bool:
        print('"{}"'.format(my_str))
        print(my_str)
    else:
        print(my_num * 2)