How do you check for special characters in a string in python?

I'd like to know if there is a way to check if a string has special characters using methods like .isnumeric() or .isdigit(). And if not, how can I check it with regex? I've only found answers about checking if it has letters or digits.

asked Jul 16, 2019 at 17:40

5

Check for any of characters not being alphanumeric like:

any(not c.isalnum() for c in mystring)

answered Jul 16, 2019 at 17:49

ipalekaipaleka

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1

Give a try for:

special_characters = ""!@#$%^&*()-+?_=,<>/""
s=input()
# Example: $tackoverflow

if any(c in special_characters for c in s):
    print("yes")
else:
    print("no")
 
# Response: yes

Ty Hitzeman

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answered Jul 30, 2020 at 13:09

mkgivkmkgivk

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3

Using string.printable (doc):

text = 'This is my text with special character (👽)'

from string import printable

if set(text).difference(printable):
    print('Text has special characters.')
else:
    print("Text hasn't special characters.")

Prints:

Text has special characters.

EDIT: To test only ascii characters and digits:

text = 'text%'

from string import ascii_letters, digits

if set(text).difference(ascii_letters + digits):
    print('Text has special characters.')
else:
    print("Text hasn't special characters.")

answered Jul 16, 2019 at 17:49

Andrej KeselyAndrej Kesely

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0

A non-ideal but potential way to do it while I look for a better solution:

special_char = False
for letter in string:
    if (not letter.isnumeric() and not letter.isdigit()):
        special_char = True
        break

UPDATE: Try this, it sees if the regex is present in the string. The regex shown is for any non-alphanumeric character.

import re
word = 'asdf*'
special_char = False
regexp = re.compile('[^0-9a-zA-Z]+')
if regexp.search(word):
    special_char = True

answered Jul 16, 2019 at 17:45

Zachary OldhamZachary Oldham

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1

Assuming a whitespace doesn't count as a special character.

def has_special_char(text: str) -> bool:
    return any(c for c in text if not c.isalnum() and not c.isspace())


if __name__ == '__main__':
    texts = [
        'asdsgbn!@$^Y$',
        '    ',
        'asdads 345345',
        '12😄3123',
        'hnfgbg'
    ]
    for it in texts:
        if has_special_char(it):
            print(it)

output:

asdsgbn!@$^Y$
12😄3123

answered Jul 16, 2019 at 17:55

abduscoabdusco

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0

Geeksforgeeks has a pretty good example using regex.

Source --> https://www.geeksforgeeks.org/python-program-check-string-contains-special-character/ Special Characters considered --> [@_!#$%^&*()<>?/\|}{~:]

# Python program to check if a string 
# contains any special character 

# import required package 
import re 

# Function checks if the string 
# contains any special character 
def run(string): 

    # Make own character set and pass  
    # this as argument in compile method 
    regex = re.compile('[@_!#$%^&*()<>?/\|}{~:]') 

    # Pass the string in search  
    # method of regex object.     
    if(regex.search(string) == None): 
        print("String is accepted") 

    else: 
        print("String is not accepted.") 


# Driver Code 
if __name__ == '__main__' : 

    # Enter the string 
    string = "Geeks$For$Geeks"

    # calling run function  
    run(string) 

answered Jul 16, 2019 at 18:02

Kartikeya SharmaKartikeya Sharma

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You can simply using the string method isalnum() like so:

firstString = "This string ha$ many $pecial ch@racters"
secondString = "ThisStringHas0SpecialCharacters"
print(firstString.isalnum())
print(secondString.isalnum())

This displays:

False
True

Take a look here if you'd like to learn more about it.

answered Jul 16, 2019 at 17:53

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