要求输入10位数字

Question

I am testing that the user input is of length 10 and only contains numbers. At the moment, my code is:

while True:
    number = input("Enter number: ")

    try:
        if len(number) != 10:
        print ("Enter 10 digits\n")
        continue

    except ValueError:
        print ("Enter only numbers\n")
        continue

    else: 
        break

The program will ask for user input, then test that it is of 10 length and only contains integers. Currently, user input is read as a string so that if it began with a '0', then this would be included in len(), if you know what I mean? For example, if I inputted '0123456789', this would be seen to have a length of 10 and not 9 because it begins with '0'. Also, I wanted to ensure that if the user entered 10 letters, this would be declined because only numbers are allowed.

Any help would be greatly appreciated. Thank you.

Answer 1

At no point in your code do you actually check that the input is an integer.. You could do something like this:

while True:
    number = input("Enter number: ")
    if not number.isdigit(): # check if a string contains a number with .isdigit()
        print ("Enter only numbers\n")
        continue
    elif len(number) != 10:
        print ("Enter 10 digits\n")
        continue
    else: 
        break

Info on str.isdigit() :

Type:       method_descriptor
String Form:<method 'isdigit' of 'str' objects>
Namespace:  Python builtin
Docstring:
S.isdigit() -> bool

Return True if all characters in S are digits
and there is at least one character in S, False otherwise.

Answer 2

while True:
    number = input("Enter number: ")
    try:
        number = int(number)
    except ValueError:
        print ("Enter only numbers")
    else:
        if 10 > number//10**9 > 0 :
            print ("Enter 10 digits")
            continue
        else: 
            break

Answer 3

You can checking for an error while casting to a number (integer)

try: 
    if len(number) != 10 and int(number):
        print ("Your number is good!")
        break

    else :
        print("Your number isn't good!")
        continue

except ValueError:

    print('only digit please')
    continue

Note that the flaw in len(number) is that the nine firsts digit could be 0.

To ensure that is a valid number beetwen 1000000000 and 999999999 you can do the following:

import math
while True:

    try: 
        if math.floor(math.log10(int(number)))+1 == 10:
            print ("Your number is good!")
            break

        else :
            print("Your number isn't good!")
            continue

    except ValueError:

        print('only digit please')
        continue