How to know if a number is an integer or a float? And how to assign a type to a value inserted in the input function

Question

I have the following problem:

Make a program that takes any two numbers (integers or real) and print on the screen the integers that are in the range understood by them.

And I made the following solution:

  n1 = int(input("Digite um valor:"))
  n2 = int(input("Digite um valor:"))

  for i in range(n1,n2):
      f(i == int(i)):
          print(i)

But I have some problems:

1. How can I make the function input take values of only 2 types? In the whole case or float.
2. How to validate if a certain number is real or integer? I tried by type but don’t know if there is another way
3. How to do the range take into account the final number of the interval?

Answer 1

In fact you do not need to check whether it is whole or float. Just use float(input(...)), which also accepts strings containing integers, so you convert what was typed to a number.

I suggest we capture the ValueError, if a number has not been entered. For ease, create a function that reads the number and already returns the value set to the range:

def ler_numero(mensagem):
    while True:
        try:
            f = float(input(mensagem))
            n = int(f)
            if f == n:
                return n
            else:
                return n + 1
        except ValueError:
            print('Digite um número válido')

This function asks for a number to be entered, and if an error occurs (i.e., a number has not been entered), it asks to be typed again.

If the conversion to float Alright, I return an integer, taking into account if the decimal part is zero (if it is 4.0, for example, then I return 4, and if it is 4.1, 4.2, etc, I return 5). For that I use int(), that rounds the float down (in case of positive numbers - for negative values, see below).

I make these adjustments because a range only accepts whole.

So now just ask to enter the numbers and print the range:

inicio = ler_numero('Digite o valor inicial:')
fim = ler_numero('Digite o valor final:')

for i in range(inicio, fim):
    print(i)

---

It is unclear whether the final value should be included (if the final value is 4.0, should you print 4 or not? ). The above code does not. If you want to consider yes, you should always add 1 after converting to integer (but only for the final value, since the initial is included).

Another detail is that the code above does not work for negative numbers as int(-3.5) results in -3 and when adding 1, the beginning would be -2 (i.e., the -3 would be left out of the range).

Then just change the function to use math.floor, rounding down (math.floor(-3.5) results in -4, and when adding 1, the beginning is -3, including him in the range):

import math

def ler_numero(mensagem):
    while True:
        try:
            f = float(input(mensagem))
            n = math.floor(f)
            if f == n:
                return n
            else:
                return n + 1
        except ValueError:
            print('Digite um número válido')

And when reading the numbers, you can also include a validation to check if the initial value is less than the final value (otherwise it makes no sense to proceed):

while True:
    inicio = ler_numero('Digite o valor inicial:')
    fim = ler_numero('Digite o valor final:')
    if fim <= inicio:
        print('Valor final deve ser maior que o inicial')
    else:
        break # valores corretos, sai do loop

for i in range(inicio, fim):
    print(i)

Answer 2

Really the way the hkotsubo said it is better, more practical and more pythonic. But just for registration title: Yes, it is possible to check if a number is float and you can do this in different ways. Some of them:

By the method isinstance():

x = 9.2
print(isinstance(x, int))
>>false
print(isinstance(x, float))
>>true

Or even with the function type():

x = 9.2
print(type(x))
>><class 'float'>