7. User Input

input is a builtin function in Python, which prompts for the user to enter as standard input unto newline(\n).

input function always returns a string datatype, we need to typecast to respective datatype required.

Python 2.x’s input is different from Python 3.x’s input.

Python 2.x’s input evaluates the string as a python command, like eval(input()).

user_entered = input("Hey Pythonist! Please enter anything: \n>>>")
print(f"The input entered is {user_entered}")

Hello Python!
The input entered is Hello Python!

Let’s try typecasting to integers we got from the user.

If the input is not a valid integer value, typecasting to integer raises ValueError

try:
    variable_1 = input("Enter variable 1 to be added: \n>>>")  # string
    variable_2 = input("Enter variable 2 to be added \n>>>")  # string
    integer_1 = int(variable_1)  # Typecasting to integer
    integer_2 = int(variable_2)  # Typecasting to integer
    print(f"sum of {variable_1} and {variable_2} = {integer_1+integer_2}")
except ValueError as exc:
    print(f"👻 unable to typecast to integer: {exc}")

output

>>>I am a string 😈
>>>I am also a string 😈
👻 unable to typecast to integer: invalid literal for int() with base 10: 'I am a string 😈'