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

Question

I m trying to check if a string only contains letters  not digits or symbols   For example    gt  gt  gt  only letters  hello   True  gt  gt  gt  only letters  he7lo   False

User · Answer

You can leverage regular expressions    gt  gt  gt  import re  gt  gt  gt  pattern   re compile    a-zA-Z       gt  gt  gt  pattern match  hello    lt  sre SRE Match object  span  0  5   match  hello  gt   gt  gt  gt  pattern match  hel7lo    gt  gt  gt    The match   method will return a Match object if a match is found  Otherwise it will return None     An easier approach is to use the  isalpha   method   gt  gt  gt   Hello  isalpha   True  gt  gt  gt   Hel7lo  isalpha   False   isalpha   returns true if there is at least 1 character in the string and if all the characters in the string are alphabets

User · Answer

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    gt  gt  gt   hello  isalpha   True  gt  gt  gt   42hello  isalpha   False  gt  gt  gt   hel lo  isalpha   False

User · Answer

Actually  we re now in globalized world of 21st century and people no longer communicate using ASCII only so when anwering question about  is it letters only  you need to take into account letters from non-ASCII alphabets as well  Python has a pretty cool unicodedata library which among other things allows categorization of Unicode characters   unicodedata category       Lo   unicodedata category  A    Lu   unicodedata category  1    Nd   unicodedata category  a    Ll    The categories and their abbreviations are defined in the Unicode standard  From here you can quite easily you can come up with a function like this   def only letters s       for c in s          cat   unicodedata category c          if cat not in   Ll   Lu   Lo                return False     return True   And then   only letters  Bzdrezylo   True  only letters  He7lo   False   As you can see the whitelisted categories can be quite easily controlled by the tuple inside the function  See this article for a more detailed discussion

User · Answer

A pretty simple solution I came up with   Python 3   def only letters tested string       for letter in tested string          if letter not in  abcdefghijklmnopqrstuvwxyz               return False     return True   You can add a space in the string you are checking against if you want spaces to be allowed

User · Answer

1  Use str isalpha   when you print the string    2  Please check below program for your reference -   str    this      No space  amp  digit in this string  print str isalpha     it gives return True   str    this is 2    print str isalpha     it gives return False   Note - I checked above example in Ubuntu

User · Answer

The str isalpha   function works   ie   if my string isalpha        print  it is letters

User · Answer

The string isalpha   function will work for you    See http   www tutorialspoint com python string isalpha htm

User · Answer

Looks like people are saying to use str isalpha   This is the one line function to check if all characters are letters   def only letters string       return all letter isalpha   for letter in string    all accepts an iterable of booleans  and returns True iff all of the booleans are True    More generally  all returns True if the objects in your iterable would be considered True  These would be considered False   0 None Empty data structures  ie  len list     0  False   duh

User · Answer

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

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

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