How can I check if a string only contains letters in Python?

Solution 1:

Simple:

if string.isalpha():
    print("It's all letters")

str.isalpha() is only true if all characters in the string are letters:

Return true if all characters in the string are alphabetic and there is at least one character, false otherwise.

Demo:

>>> 'hello'.isalpha()
True
>>> '42hello'.isalpha()
False
>>> 'hel lo'.isalpha()
False

The str.isalpha() function works. ie.

if my_string.isalpha():
    print('it is letters')

For people finding this question via Google who might want to know if a string contains only a subset of all letters, I recommend using regexes:

import re

def only_letters(tested_string):
    match = re.match("^[ABCDEFGHJKLM]*$", tested_string)
    return match is not None