Using startswith() to detect blank input

while True:
    familar_name = input('Enter your name: ')

    if familar_name.startswith(""):
        print('Please enter a valid name')
    elif familar_name.isalpha():
        print('Hello', familar_name)
        break

I'm trying to detect a blank input. elif statement never met even when entering an alphabetical input.

A string always starts with an empty string, this condition is True. That's why your elif statement doesn't work:

a = "hi"
if a.startswith(""):
    print('yes')

output:

yes

In order to check the blank input, you can just check for truthiness of the familar_name like :

name = input('enter your name')
if name:
    ...

The above if statement's body will execute if the string is not blank. But this will fail if user passes whitespaces. So maybe you need to use .strip() before that checking.

Also don't forget to call .isalpha method --> .isalpha()

use " " instead of ""

while True:

    familar_name = input('enter your name') 

    if familar_name.startswith(" "): # you have to have a space here.
       print('Please enter a valid name')
    elif familar_name.isalpha():
       print('Hello', familar_name)
       break