Convert strings to int or float in Python 3?

Question

 integer = input(\"Number: \")
 rslt = int(integer)+2
 print(\'2 + \' + integer + \' = \' + rslt)
 double = input(\"Point Number: \")
 print(\'2.5 + \' +double+\' =          


        

Answer 1

In Python 3.x - input is the equivalent of Python 2.x's raw_input...

You should be using string formatting for this - and perform some error checking:

try:
    integer = int(input('something: '))
    print('2 + {} = {}'.format(integer, integer + 2))
except ValueError as e:
    print("ooops - you didn't enter something I could make an int of...")

Another option - that looks a bit convoluted is to allow the interpreter to take its best guess at the value, then raise something that isn't int or float:

from ast import literal_eval

try:
    value = literal_eval(input('test: '))
    if not isinstance(value, (int, float)):
        raise ValueError
    print value + 2
except ValueError as e:
    print('oooops - not int or float')

This allows a bit more flexibility if you wanted complex numbers or lists or tuples as input for instance...