How to convert int variable to string without deleting zeros?

Question

Need to perform in an activity the validation of characters typed by the user.

My code:

mes1 = int (input ('Digite o mês inicial:'))
valida = len (str (mes1))
while valida != 2:
    print ('Valor inválido! O mês deve ter 2 dígitos.')
    mes1 = int (input ('Digite o mês inicial:'))
    valida = len (str (mes1))

The problem is that when I convert int to string in the'validate 'variable, zeros are disregarded. Ex: Type month 12, all correct; Type month 02, error.

Error image:

Answer 1

An integer value has no zeros left; if you need to keep them you should keep their value as string, but if the intention is to do this to validate a month, don’t. Month 02 is the same as month 2, so validating if it has two characters is not a sufficient validation (42 is a valid month? It has two characters).

If you wish to validate whether a number has been entered and if it is a valid month you will need to treat the exception ValueError which is launched by int when the value is not numerical and to know if it is a valid value for the month just check if it is between 1 and 12 inclusive. Theoretically if I enter "month 2" or "month 02" should be the same thing, then it cannot validate if there are two characters.

while True:
  try:
    month = int(input('Mês: '))
    if 1 <= month <= 12:
      break
    print('Informe um valor entre 1 e 12')
  except ValueError:
    print('Informe um valor numérico')

When executing you would have an exit like:

>>> Mês: a
Informe um valor numérico
>>> Mês: 13
>>> Informe um valor entre 1 e 12
Mês: 5

^{See working on Repl.it}

Important note: One string with zero left is completely different from a value with zero left. In Python 2 the left zero on an integer was used to indicate that the value was octal, that is, base 8 and not base 10. Do, for example, print(010) in Python 2 will display 8, as the number 010 in base 8 equals the number 8 in base 10. In Python 3 this notation has been changed to 0o10, with the letter o between values and started generating a syntax error for integers with 0 left. Be very careful not to confuse things.

Answer 2

It’s simple, don’t convert to whole, if you already have the information the way you want it, then use it directly. If you need the conversion, do it after validating. In the end I did the conversion if you still need it, I don’t know if you really need it, it could be a conceptual error there.

I took advantage and removed the redundancy code, now the request appears once, respecting the DRY. improved the organization of the code.

while True:
    mes = input('Digite o mês inicial:')
    if len(mes) == 2:
        break;
    print ('Valor inválido! O mês deve ter 2 dígitos.')
mes1 = int(mes)
print(mes1)

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

Answer 3

Face there is no integer with 0 on the left side 01 == 1 , then reads the input as string and makes string comparison.